Pancolitis caused by UC: Have you been through this?

My 20 yo son began rectal bleeding on Nov 30. Dec 1 he had a CT - normal. On Dec 17 he had a colonoscopy. Doc said he saw inflammation and ulcers. Dx him with UC. Told him to take Lialda but to wait until the biopsy results come back "in case there is a surprise". He did have him start suppositories while waiting.

While still awaiting the biopsy results, he felt dizzy and was scared he was losing too much blood (still bleeding every day). He went to the ER. At this point he was still only pooping 1 - 2 times a day, not diarrhea, but not totally formed. The ER doc reamed him a new one for "not taking the LIalda" and told him to go home and start it. He did. Within hours, the cramping started. I found him in a fetal position on the couch, toes curled near tears. Two nights later the real problem started. He began going to the toilet every five minutes and it was all blood - no poop. In the morning, he placed a call to his Dr. and he said to go the the ER.

He gets to the ER and they do a CT. Tell him he now has pan colitis. They admit him. The ER doc said his previous dx was not supported by his history and physical, clinical studies, nor laboratory studies. This is when we found out the biopsy results from the colonoscopy did not find any histological changes, chronic inflammation or evidence of UC. Hmm. The ER doc said "Most likely infectious colitis". I just saw this on his record after ordering them yesterday - we were not aware of this until now. All I knew during his ER stay was what one doc said "You know, it is weird, his colonoscopy did not show inflammation".

He's admitted and placed in IV prednisone, flagyl and Cipro. The doctor kept me very informed, with discussions every day. He was great. Four days into his admission the doc said he may need to remove his colon. I asked the doc to think outside the box. I told him I had heard his colonoscopy had not shown any chronic inflammation - there was inflammation, but it had just started. . He said I was right. I also mentioned that NONE of his inflammatory markers were elevated - normal ESR SED rate, CRP and platelets. They had not done a calprotectin at this point. The doc decided to do another colonoscopy.

It took them another three days to get him in for his colonsocopy (even as an inpatient!!) A different doc did his colonoscopy. Biopsies said "chronic inflammation" - I am guessing since the inflammation had been there for a week at least (pan colitis symptoms) then it said chronic. The next day they send him home on oral prednisone. 60mg. They did do a calprotectin which came back at 2550 - but we were told the prednisone can cause that to rise, especially IV.

Every single one of his blood tests for inflammatory markers were NORMAL.

Fast forward to his 16th day post admission. He has literally no symptoms. Poop fully formed, no blood, no diarrhea, no cramping, no fatigue...he has now tapered down the prednisone to 20 mg. Still all good.

He did start Eleyta infusions. His symptoms disappeared prior to his first infusion. He has had two now. He will have another one on March 10 - then every 8 weeks for the rest of his life.

My concern is that it seems there is a possibility it may not be a "classic case" of UC or Pancolitis. I'm also concerned in that they asked him if he took Ibuprofen or Motrin. He said no. He did not realize Advil is the same. He tore his ACL in his knee last year and was taking it regularly - sometimes 800 mg.

Does pan colitis come on in less that three weeks from normal? Can it go away that quickly? I really worry about him being on these infusions long term - especially if this was caused by something other than IBD. Oh..he also was diagnosed with diverticulosis at the ripe age of 11 - totally verified by his docs and Stanford University. Never had an issue - but some of the pain he had with this was his left side - during his hospital stay and during some of the rectal bleeding. His first colonoscopy said his left colon was "Benign, normal mucosa".

If anyone has any insights, I would really appreciate it! Thank you.