Sounds like you've run the gamet of tests and Dr's with everyone scratch there heads as much as you. If you have had lymes, those symptoms can come back especially if you didnt fully get rid of it before. But thats the other thing, if you have had a positive lyme test you may not always get a positive test if you have been exposed again. Thats what happened to me, got lymes one summer and a year later had all the symptoms with a negative test. Its not until I went to the rhumy that they did a more in depth test which came back positive. Of course thats not always the case which makes lymes a huge pain in the bum.
You know your body better than anyone else, if something is telling you to keep looking just go woth it. If you still have a feeling like you should keep following the trail, so to speak, I would really strongly suggest a rhumy, any test which they have done, even for autoimmune, a rhumy does that much more in depth. There kind of the last resort Doc, they can often find answeres to the medical mysteries other docs get stuck on. But you know whats best for you.
Good luck with whatever you decide.
In suffering, we are given the key to a door which most rarely
get to open. Behind it lies the ultimate gift which is only visible
in our darkest hour.