Welcome to NT
You have come to the right place for support and good information.
MS is not easy to deal with. I pray it's not that.
You seem to have gotten somewhat better, walking after PT. I'm not a doctor, but that's significant improvement.
If you can, find comfort in knowing that all those expensive tests are not showing other things, like cancers, tumors, diabetes, and other difficult conditions to cohabitate with.
It's hard when you don't know. Scary is more like it.
If you have the MRI and a consult and you still don't know, look farther down the road for another doctor. I'm sure your doc is good. I'm sure he's troubled about it too. Doc should refer you out.
I gathered morsels along my journey of physicians, until I got lucky with Dr. Atasoy. He's a surgeon but he also saw me as a whole person and helped my other conditions, too.
Here is the link to the Stumble Inn, in case you haven't found it yet.
http://neurotalk.psychcentral.com/forum17.html
Sometimes it takes a while to get a dx. don't give up and try not to be too discouraged.
Keep asking questions.
If you keep a journal, you may discover a pattern to help you and your treaters. Make it as complete as you can. Include meds, vitamins, foods, etc.
Take care... (BW)