I realize that I am just jumping in the middle without a full picture here, but wondered if you have had the opportunity to read about or try biofeedback. It may be something that could help point you in a direction to go at this point as well as help your body where it is now. It was through biofeedback that I initially became aware of the heavy metal toxicity in my body. You have completely different symptoms than what I have experienced so I couldn't give you guidance on supplements or what your body might need and that is why I thought to suggest trying biofeedback. If you go to Ondamed.net they have a link that could help you find someone in your area to go to.
I know what it feels like to go months and years on end continually going downhill. My prayer will be that you can find what it is that your body needs to help you combat this.