"After several CAT scans, MRIs and an angiogram, [doctors] decided to keep Michaels in the ICU and are running several tests to determine the cause. [It] will be touch and go for the next few days while he is under intense observation," a source close to the situation told People.
This hospital visit follows an April 12 emergency appendectomy at a hospital in San Antonio, Texas. Michaels remained in the hospital under his doctor's care following the procedure, then transferred to a rehab facility specializing in diabetic patients.
No word on whether this new development is related to Michaels' appendectomy or his diabetes.
"They told me that if I had gone on stage like I wanted to, [my appendix] likely would have ruptured and I could have died," he wrote in a note to his fans. "There is just no way around the fact that getting your appendix out HURTS. I have a pretty good threshold for pain, but this one hurts."
Wonderwall will keep you updated as this story develops