Fibromyalgia and CFS are often intertwined. Some doctors are very biased against diagnosing CFS, thinking it is an "imaginary disease". Can't hurt to be assessed and/or referred to a specialist, especially if you have other symptoms such as fatigue, "brain fog" and depression. Try that website as well and let us know how it all goes.
I do have fibromyalgia. Have been diagnosed with this 8 years ago.
I'm not a doctor, so these are just my thoughts, but you have some similar symptoms to a friend of mine who has Chronic Fatigue Syndrome, which is often undiagnosed. She has a distended belly and bladder control problems, but not the lack of appetite. I think the important thing is that you keep pushing the doctors to look at other possibilities medically until they find what is wrong with you. If you feel they are not listening to you, then consider a second opinion or just switching doctors. You might also want to post on another board such as gastoenterology to see if other people have similar experiences (and maybe even fibromyalgia/cfs just on the off chance).
I have my thyroid checked regularly ever since I had my hysterectomy and there is nothing wrong there. I don't deny myself food, actually, I force myself to eat what little I do. None of this makes sence to me and I am worried. I look like I am 9 months pregnant when I am not. I have bladder control issues that make no sence and all my doctors are baffled.
It sounds like you are not feeling hungry and denying yourself food which would indicate an eating disorder. I would definitely check in with your doctor. If you are eating very little and gaining weight, I would get your thyroid checked.