@turtlegalsandy - What an ordeal you have been through!
I also had a sigmoidoscopy some years ago for severe diarrhea. The biopsy showed collagenous colitis - about same as lymphocytic colitis.
I was treated with weekly injections of Metothrexate for a month. The diarrhea disappeared. I was told that it might return. Not yet. It can also be treated with steroids.

Did you ever have a full colonoscopy and endoscopy? CT scans or MRIs?
I hope you can be treated shortly.
Please follow up with us!