Hello @gohan, Welcome to Connect. Sorry you have been battling this condition for 15 years. I'm wondering if some of your symptoms line up with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) which has symptoms that include unexplained weight changes, as well as muscle pain, brain fog and allergies to food.
--- What to know about chronic fatigue syndrome: https://www.medicalnewstoday.com/articles/184802.

If you think it might be certain foods making your symptoms worse, the FODMAP diet may help you determine which ones. The FODMAP diet is an elimination diet to determine food intolerances in people with irritable bowel syndrome (IBS). It requires the elimination of fermentable carbs for 4-6 weeks, and then reintroducing one food at a time to see if symptoms recur.
--- A Map for the FODMAP Diet: https://connect.mayoclinic.org/blog/gastroenterology-and-gi-surgery/newsfeed-post/a-map-for-the-fodmap-diet/.

You might also find the following discussion helpful:
--- Chronic Illnesses of Millions of Women Left Untreated: https://connect.mayoclinic.org/discussion/chronic-illnesses-of-millions-of-women-left-untreated/.

Have you thought about seeking help at a teaching hospital or major health facility like Mayo Clinic?