Hello and welcome to the forums! Thanks for your question and we are certainly sorry you have been feeling so ill! This sincerely sounds like it has been horrific for you. And I understand about the issues of maintaining your job which is so important. You do have symptoms of ulcerative colitis. https://www.mayoclinic.org/diseases-conditions/ulcerative-colitis/symptoms-causes/syc-20353326. This has a symptom list that you can see includes Abdominal pain
Blood in your stool
Ongoing diarrhea that doesn't respond to over-the-counter medications
Diarrhea that awakens you from sleep
An unexplained fever lasting more than a day or two
However, a stool sample can also help determine if colitis is the cause and it doesn't sound like that panned out. They may opt to do another stool test or colonoscopy which would be helpful. I would also do blood work to make sure you aren't anemic which very well could be at this point. I would ask for more testing based on your symptoms. Remember that ulcerative colitis is immune system related as well so you want to make sure your doing your best to have a healthy immune system as well.
Something else to consider is irritable bowel syndrome. https://www.medhelp.org/gastroenterology/articles/Irritable-Bowel-Syndrome-IBS-Overview/233 Your
symptoms seem like an extreme version of those you find with IBS.
Have they recommended anything to address the inflammation in your bowels as shown through high calprotectin levels?
Also, are you scheduled to see a gastroenterologist soon? I would call them and see if you can move the appointment up. They often have cancellations or can work someone in as your situation is currently at a high level. So, I'd try to do that.
Please let me know how this goes.