That is a lot of great info and possible avenues to search, Matt - Thanks
I posted my seemingly unique symptom (a brief thump in intestines in the same spot) a while back and got an answer from someone who had similar and cured with Pyrantel over 2 weeks. Here is a link to the thread.
I will do the same to see if anything resolves, or if there is anything in stool.
Then I'll take a closer look at your suggestions.
I can only think that something large enough for me to feel in my intestines has to be some sort of parasite.
Curiously, my Dr suggested B12 and Zinc, which have reduced the muscle twitching in my muscles a lot. It looks like that was electrolyte or similar imbalance.