Not a doctor (although I imagine there are some here) but have had my share of "GI issues" in the past.

Some questions I was asked when trying to figure out my issues:

• When you say "severe GI issues" are you specifically talking diarrhea? Vomiting? Abdominal pain?
• Do you have issues only when running or is it persistent throughout the day?
• Any "red flag" symptoms, like unexplained weight loss, blood in BMs, fever, nocturnal BMs, or family history of IBD or colon cancer?
• Did you have an endoscopy done? Any suspicion of a food allergy (lactose intolerance or celiac disease)?
• Are you under increased psychological stress?
• Any change or improvement based on how long you wait after a meal before running? Or running on a completely empty stomach in the morning?

Post this in the Lavender room as I believe "Duffy" was experiencing some of the same issues.

So urgency and diarrhea are the primary issues. Blood is common.

Used to be tied to running but now persists. Latest episode actually began while on a running break and had continued for several weeks.

Weight loss always follows as nothing stays in system too long. I’m pretty thin naturally (6” 155-160) but can drop under 150 pretty easily during bouts.

Have done limited food allergy testing with pretty general triggers. Diet is pretty bland - rice, chicken, beef, veggies. I do have pizza occasionally but it is a trigger. Have cut out pasta, drink very minimally, yogurt as only real dairy source. I do indulge my sweet tooth but doesn’t seem to make a difference.

Siblings with colitis issues but they presented early in life and have treated it long term.

How old are you (approximately) if you don't mind me asking? Has there been any discussion of potential irritable bowel syndrome diagnosis with your GI doc? I assume IBD has been ruled out based on the blood work and colonoscopy and that the original diagnosis was microscopic colitis rather than ulcerative colitis.

Does OTC (like Imodium) help at all? Are the bouts of GI distress tied at all to emotional stress?

Assuming there are no "real" identifiable GI issues it kind of sounds like IBS-D to me. I'd consult with your GI doc again but there are a few potential treatments if that's really what it is.

Imodium or loperamide is kind of the first thing to try. Psyllium husk supplements can work as well if it is a fiber issue as it adds bulk to the stool and absorbs some of the water from the intestine. If it's a bacterial or gut microbiota issue there is a newer antibiotic regimen called rifaximin or Xifaxan that lasts a few weeks and is supposed to basically reset the gut microbiota.

There is also a newer drug called Viberzi that is basically similar to an opioid that slows gut motility and reduces abdominal pain but it's expensive and kind of a last resort.

Another thing to consider would be bile acid malabsorption if it's frequent, watery stool that is worsened with fatty meals. There are some tests available to diagnose it and the treatment is to basically take a bile acid binder with meals.

For me the problem has always been stress related so an antidepressant helped the symptoms immensely.

As I mentioned I'm not a doctor but have dealt with similar issues for a long time and done extensive research. Best of luck to you as I know how much of a pain in the ass it can be.

Celiac disease?

I am turning 50 in April.

Imodium has actually been my go to for years the night before or morning of a race. Has always allowed me to at least get through a race without real issues. I have noticed it is less effective currently. Took one recently to just basically get through the next workday unscathed whereas it used to bind me up for a couple days. I don’t mind taking one occasionally but cannot imagine popping them like aspirin in preparation for any real run workout.

I am seeing my GI doc again early Jan to see what next course of action is but anything I can bring to the table that hasn’t been looked at is hopefully a step closer to resolution. Ultimately I guess if I have to accept being healthy without being able to run I can adjust but it will be tough. Had Boston on the schedule this year just as a bucket list race and was going to roll it over but we will see.

Point 1) I would check out a book called "the Athlete's Gut" - you might find it very helpful.

Point 2) I am honestly very surprised that no medications have been tried except steroids. Mesalamine is a drug that is prescribed for both inflammatory bowel disease and IBS - I'm surprised it was never raised or tried given your issues. (of course, I am neither a doctor who has examined you nor a doctor at all, so please don't take this as a suggestion that you should be on it - just mentioning as something to raise with your doctor).

FWIW, I have ulcerative colitis. I started developing symptoms like yours close to 20 years ago. Have had numerous flex sigs and colonoscopies. For a while everything came back clean and my DX was IBS. Then they noted some irritations and I was changed to "indeterminate colitis." Then about 18 months ago another colonoscopy showed ulcerations and the pathology came back supporting ulcerative colitis. So a clean colonoscopy doesn't necessarily mean that you don't have IBD.