Hi, I am not an expert by any means! but your story seems similar to mine. I had major digestive problems and no matter what I did in terms of exercise, supplementation, bowel cleasing, nothing seemed to make a difference to my weight. I then had a thyroid test - not by a doctor but by a private lab that determine whether your thyroid level is right for you as an individual and not whether it falls within broadly set parameters - (I mention this because I previously had two negative thyroid tests done by my GP) and it showed that mine was underactive.
I started taking Natural Thyroid Supplements (thyroxine free) and over the course of about 6 months I lost 3.5 stone and now weigh what I used to when I was 19 just before my digestive issues started.
Also I had major gum problems - bleeding and gingivitis - that were seriously helped by bowel cleansing.