Nurse!

Bret Michaels was rushed to the hospital late Thursday night after suffering a massive hemorrhage near his brain stem, this according to a rep for the singer.

Michaels is reportedly in critical condition at an undisclosed hospital. According to the rep, Michaels was suffering from excruciating headaches earlier in the day.

Michaels underwent several tests, the rep says, including CAT Scans and MRIs.

Michaels suffered from a "subarachnoid hemorrhage" -- bleeding at the base of his brain stem.

Earlier this month, Michaels was rushed to the hospital after experiencing stomach pains -- he ended up having his appendix removed.

Alves was leaving OTM Fight Shop in Redondo Beach yesterday, where he told us he's not only doing well, he's already training again -- just weeks after a surgical procedure to prevent bleeding in his brain.

The newly-minted TBS late night host told photogs his tour manager had to be checked out after exhibiting some sort of "symptoms" -- but Conan wasn't specific about the nature of the illness.

And while Coco was all fired up about the free health care in Canada, he joked "I think they're gonna take his American Express card ... because we're American."

The comedian nearly got his ass arrested earlier last week when -- according to the 911 caller -- he drunkenly barreled into her L.A. home in the middle of the night.

We're told the victim didn't want to press charges and cops simply drove Andy home.

Bret Michaels was set to explode on stage at Sea World last night -- instead, his appendix almost burst.

The Poison frontman was rushed to the emergency room in San Antonio around 1:00 AM after he complained about severe stomach pains.

Once he got to the E.R., it was determined that Michaels was suffering from acute appendicitis. According to a rep for Michaels, the singer was treated -- and is beginning the recovery process.

No word if docs had to remove the appendix.

Taylor tells TMZ she was driving through Fort Worth on I-35 North Tuesday afternoon when the car in front of her rear-ended another car ... and she didn't have enough time to stop before she came crashing in too.

According to Taylor, the Hummer received around $14,000 in damages ... and she had to spend six hours in a nearby hospital for the concussion she suffered ... as well as a sprained neck and bruised shins.

After Puck drove the car into a ditch in San Diego last month, his son managed to crawl out of the wreckage and flag down a person with a cell phone who then dialed 911.

With injuries to several internal organs, Puck's son calmly explained the situation to the caller -- who relayed the info to the 911 dispatcher. Both Puck and his son were hospitalized with multiple serious injuries.

A rep from the Beverly Hills PD tells TMZ the accident occurred Monday around 4 PM -- emergency vehicles responded to the scene.

A witness tells us it didn't appear that anyone was seriously injured in the wreck.

A rep for Poitier had no comment.

UPDATE: The Beverly Hills PD released a statement saying, "Poitier was driving a dark colored Mercedes Benz northbound when it collided with a dark colored Porsche."

According to cops, Poitier was not injured -- but a passenger in the Porsche was transported to UCLA Medical Center with non-life threatening injuries.

An investigation is underway.

According to the docs, on September 23, 2009, Dr. Michael Brownstein performed the operation.

The specifics of the procedure are not outlined, but the Dr. says, "Chaz Bono has completed his gender reassignment surgery."

UFC's Thiago "Pitbull" Alves will not fight at Saturday's UFC 111, because a CAT Scan shows an irregularity in his brain ... TMZ has learned.

Thiago was scheduled to rumble with Jon Fitch on Saturday -- but a pre-fight CAT Scan revealed an irregularity -- a source close to 26-year-old Pitbull tells TMZ the irregularity involves an artery in the brain.

UFC honcho Dana White tells TMZ he will fly Pitbull to a specialist for further evaluation. White says, "If it's true, it can be career-ending."

No one will replace Pitbull on Saturday. The headliner is Georges St- Pierre -- ironically, the fighter who solidly beat Thiago in his last fight last July.

Puck from "The Real World: San Francisco" is hospitalized in San Diego following a terrifying car wreck that left the reality star and his 8-year-old son seriously injured ... this according to sources close to the family.

We're told Puck was driving down Route 79 on Friday to go on a father-son fishing trip, when he swerved to avoid a deer and lost control of his car.

The car rolled down an embankment and landed upside down in a creek. Sources tell us Puck -- real name David Rainey -- was trapped, but he managed to free his son, who flagged down some help.

The two were transported to nearby hospitals where doctors discovered Puck had broken bones in both feet, his right hand, his neck ... and fractured his sternum and clavicle.

We're told his son had bruised several internal organs in the wreck -- he also suffered major damage to his liver.

Lindsay Lohan's dad had a heart attack today, according to his girlfriend/non-doctor Kate Major.

Michael Lohan was taken to a hospital in New York after suffering chest pains that radiated to his arms. Kate says an EKG showed evidence of a heart attack.

Kate says Michael is at St. Francis Hospital in Manhasset. She says Michael will undergo a "procedure" but wasn't specific.

Back on March 6, Michael suffered chest pains and was told by his doctor that he needed a heart catheterization.

When Kendra was questioned about shrinking her swelled parts during a taping of "Lopez Tonight," the entire audience booed -- and even hubby Hank Baskett said he's gonna "miss 'em."

Erica "Rikki" Mongeon is finally starting to show signs of improvement after an accident last week left her in a medically induced coma.

The "Ikki Twin" from MTV's "A Double Shot of Love" is not out of the woods yet, but Mongeon's manager tells us her eyes are open and she's responsive. Doctors have reduced Erica's medication and replaced her breathing tube with an oxygen mask.

Erica and her sister Victoria were passengers in a car that collided with a semi-truck in Bakersfield last Tuesday. There were no other serious injuries.