hi Deb-wow you are having it tough. So pleased to see that you are taking charge. Medical science has lots of gaps.
My daughter has severe M.E. (it is her website in the link) which she has extensively researched as there was just nothing of use out there.
As she is house-bound the number of tests she has had is limited, though she does get home kits for blood tests.
There is no known cure for M.E., just suggested treatments.
The good news is that she is getting better exponentially! It's been gradual up to now, but we can see a marked rate of improvement.
The problem is that as she takes so many things, has revised her diet several times, and does other things that are meant to help, she doesn't know what is working and what is not.
Diet is a major factor and she is now on fresh juices, lightly cooked vegies, meat daily, no dairy, wheat, sugar, yeast, manufactured foods, soft drinks, alcohol and so on. Distilled water now, and she uses a sauna for detoxing. No chemicals in anything.
I guess it is unlikely that you will be any different, so you just have to keep plugging away.
One aim is to find the cause or causes, the other is to rebuild the immune system to cope.
Have you looked into multiple chemical sensitivity? My daughter was exposed to several flea bombs before she became ill, and we wonder if these compromised her immune system.
I hope this gives you some encouragement.