I feel so badly for you. I know you likely hear that often enough but I just do.
I also don't understand how your PT can determine there's nothing they can do for you anymore... surely there is something that can help.
Please forgive me I can't remember if you've seen a neurologist yet?
Haven't been in your shoes, so thinking the only thing I can offer is a hug of support. I hope someone here or on your care team can offer something! I'm so sorry this is happening to you.