Please chime in, constipation but physllium irritates my colon, what to take to get a good BM

Have you tried something like Citrucel? I don’t know how fbitnwould help or not. Someone here takes it, but I can’t recall who it is at the moment.

My GI suggested Miralax to me, but it seemed to irritate me the two times I've taken it (once it was as part of a prep and it's the only time I have ever gotten super sick during a prep). The second time, it didn't help and I ended up flaring super bad a couple days later. Could be a coincidence. I feel like I look pregnant a lot of the time too!

Citrucel works for me and no other fiber pill is tolerated by my gut.
I cannot remember--are you allergic to mesalamine enemas? They really help with constipation because it helps lower inflammation and allow the rectum to let go (my description lol).

Fiber in many foods constipates my gut. It just cannot move that along and does much better with low fiber food especially meat and potatoes. Small amounts of cooked spinach and baby carrots help firm things up.

Good luck.

I think magnesium is the most gentle thing. Natural calm makes a tasty drinkable formula

Citrucel kicked in, mild cramping in front and lower area , but no pain on left side of colon. I emptied quite well

With psyllium fiber, the fiber itself is a simple mechanism. It's the individual variances in our guts that are complicated. Fiber is recommended generally by doctors because in most cases it doesn't cause lasting damage and so is considered safe to try. This doesn't mean it always helps but is generally worth a shot.
With acute diarrhea as an example, soluble fiber can soak up excessive liquid to help slow the rush and create a more solid mass. With relative volume based diarrhea, it is more hit and miss though as diarrhea tends to results in excess stool volume and fiber tends to add more volume resulting in more bathroom trips. Constipation has many variables as well, diarrhea or constipation can be due to nutrient absorption issues, digestion, inflammation, peristaltic issues and electrolyte transport just off the top of my head.
Summary would be it's almost impossible to calculate all the variables of your intestines and say fiber will or will not help but it has shown enough effectiveness and is a cost efficient trial.

Magnesium citrate is most likely your solution. Following is from my own perspective and what helped me personally. Check if you would like to give a try.

You will have to trial Mg Citrate at a wide variety of doses. First, check your tolerance dose. Its the dose at which you get almost loose motions. 2/3 of that dose is required to keep the bowels moving. This, not only applies to psyllium induced constipation but almost every other aspect where you would like to keep bowels moving (except for the case of low muscle tone induced constipation).

Mg Citrate pulls water in the gut and keeps the psyllium 'wet'. Wet psyllium induces peristalsis, leading to constipation relief. If you have dried stools in the gut, do it very slowly or it will bother you more.

IMO, Psyllium husk is not good for us due to lack of soluble starch and relatively abrasive compared to the psyllium seed powder. If you like, you can switch to Psyllium seed powder (Starwest Botanical on Amazon is what I use, no affiliation, just a happy customer) and repeat the experiment. Soluble starch in the seed powder also acts as a prebiotic.

Metamucil is a husk, powdered. The 'feeling' of Metamucil vs the seed powder is different (to me). I personally can not live without psyllium seed powder. I will skip food but not seed powder.

FWIW, I am in remission for almost 5 years now, after a lot of fiber trials. Currently, I have my own prebiotic mix that helps me. Still, sometimes, I end up in gut flora induced depression. I do Mg Citrate or Vit C flush and the feeling changes markedly, most likely because these flushes remove a good amount of gut flora (just like colonoscopy prep, just not that bad). I am at this point, I don't care how it works, but the feeling better is lot important. I have gone through my own dog days due to UC. I just don't want to see those days again.

Psyllium, caffeine, and jogging can all cause diarrhea. Gut bacteria thrive on psyllium. It contains cellulose and lignin and is mucilaginous. These may be great in feeding your good gut bacteria, but gut dysbosis is common with those with ulcerative colitis. The psyllium also feed the bad bacteria, and if you have an overgrowth of bad bacteria, then they can make your diarrhea and ulcerative colitis flareups worse:

http://www.breakingtheviciouscycle.info/legal/detail/psyllium-husks/
http://www.breakingtheviciouscycle.info/knowledge_base/detail/mucilaginous-polysaccharides/

There are substances in coffee that irritate the gut:

https://www.webmd.com/digestive-disorders/news/20100322/brewing-gentler-java

I do triathlons. Running can cause the runs:

https://en.wikipedia.org/wiki/Runner's_diarrhea

So how not to get diarrhea? That's a hard one. It really depends on how bad it is. Currently, I consume a lot of high fibrous non-starchy, non-mucilaginous plants, but I couldn't do that during previous flareups because my colon was inflamed. Soups with meaty bones and vegetables are a way to get nourishment without being hard on the gut.

Before I run, I'll have a small snack consisting of fruit with nuts to give me the sugar and protein I need for the run because the sugar and starch sugar sports drinks, gels, ... gives me diarrhea. They have a high glycemic index, which increases inflammation.