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.
UPDATE: Bret's appendix was removed.