'90 Day Fiancé' Star Nikki Exotika Hospitalized For Emergency Quadruple Bypass

Nikki Exotika went to the hospital for an emergency heart surgery ... and it turns out she had more blocked arteries than doctors thought.

According to her mom, Myrna, the '90 Day Fiancé' star was supposed to have triple bypass surgery, but ended up needing a quadruple bypass instead -- AKA four of her arteries were blocked and needed grafting.

Mama Myrna said her daughter was in surgery for 7 hours and had about 25 people working on her ... adding that her daughter had to be put on a breathing machine until she was able to breathe better on her own.

In her Instagram update, Myrna said Nikki is "gonna be out for a while" ... and she's set up a GoFundMe to help the reality star pay her rent while she recovers from the scary surgery.

Mama Myrna writes on the GoFundMe that Nikki had been having chest pain, heartburn, shortness of breath "for quite some time" ... but got a clean bill of health from both her doc and a cardiologist.

She said that Nikki almost collapsed during a recent performance ... and from there everything seemed to happen really fast.

On her way back to the cardiologist, she suffered a mild heart attack and was rushed to the ER, her mom says.

An angiogram showed that the blockages in her arteries were "too extensive" for stents or an angioplasty ... so she needed the bypass.

Myrna says the emergency surgery is covered by Nikki's insurance ... but is turning to crowdfunding to keep the lights on during the "long and difficult" recovery she's facing.