I have a type of microscopic colitis, collagenous colitis. Some dr.s don’t believe in it. You have to ask your gastro if they believe in it.
When they do a regular colonoscopy the dr. Has to take several large biopsies to find it. The dr.s Can’t see it so they are just hoping to catch it in a sample they send the lab. Took me 11 years to get diagnosed. I hope you find out what’s going on soon.