I had new onset neuropathy 12 hours post first moderna vaccine. I did get covid tested just to rule out and it was negative. You can also get a nucleocapsid covid antibody test that would only be positive from a past covid infection not from vaccine. You just have to make sure the correct one is ordered bc the other antibody tests (that test for spike protein) will be positive after vaccine. My nucleocapsid was negative. I don’t have any answers for you but I share your frustration!