Your symptoms strongly suggest strongyloides to me. This worm does more damage to the colon than any other I can think of. It caused me to have malabsorption and maldigestion with resulting weight loss and muscle wasting. Strongyloides also paralyze the colon and cause constipation.
ICU's treatment for strongyloides is the same as for morgellons. Albenza is the primary RX for this protocol. This is not the gold standard. Check out CDC dot gov for treatment suggestions.
Ivermectin is the best RX to use and it can be administered rectally for sure absorption--this method is also systemic. The vet horse paste is very inexpensive. I have posted on this before. I believe the standard of 12 mg/day of ivermectin has been increased to 18 mg/day.
I also had/have mites. Ivermectin does not work for mites but albendazole does. I believe the 200 mg dose twice a day works for mites. This treatment needs to be for months.
By the way, strongyloides are not visible in your stool.
The colon can't heal until the strongyloides (or whatever you have) are under control and it took me several months. I did take HCL and digestive enzymes which was a turning point for me. You need to keep your colon moving and magnesium citrate is good for that.
I have also acquired candida somewhere along the line and a good and cheap treatment is Lugol's iodine.