Upcoming video visit this week. It was only last week that it crossed the line from “annoying as heck” to “something’s got to be done”.
I’ll just say that it sounds like your situation is considerably more, um, impacted, and you’ve done a reasonable job of exhausting OTC remedies. For me, a fiber-rich diet and magnesium take care of it.
To be sure, modification of diet might not be relevant to a particular individual’s problems with gut motility.
That said, there’s two primary types of fiber - soluble and insoluble. Psyllium is high in both and, frequently, the problem that people have is that they’re deficient in both. If that’s not the issue though, one type of fiber (soluble?) tends towards slowing things down and the other (insoluble?) tends towards speeding them up. If you’re getting sufficient fiber but the balance isn’t good then psyllium didn’t do much to shift that balance. You may want to try a fiber source that’s less balanced between the two types.
And that’s just assuming that there’s nothing more to fiber other than the two types.
For example, this study breaks things down into several dozen categories and analyzes the effects of nine.
If you haven’t found an answer yet, there’s nothing like using yourself as a guinea pig.