@marriedto41- I understand how frightened you and your wife must be. It is good that you will see a rheumatologist. May I ask if your son has bloodshot eyes and reddened lips and young? Peeling skin?
I have experience in Pediatrics from my past. To me the combination of the symptoms and the lab findings point to something called Kawasaki’s Disease. Most common in very young children, could possibly be triggered by a virus. I guess you can include it in rheumatic diseases - vasculitis, inflammation of the blood vessels. It is not easy to diagnose at once, it has to be followed with labs and exams and even echocardiogram. Please keep us up to date after your visit Thursday!