@sunnyred2247 You sound like me about 5 yrs ago! I didn’t have diarrhea, but i did have almost explosive vomiting for no reason. The anti-nausea/vomiting meds the gave me didn’t stop anything. I lost 20 pounds. When i was almost non-responsive, i got an MRI which “showed inordinate amount of white lesions on my brain.” Most doctors only thought of MS, but it wasn’t. When i was almost non-responsive, my husband took me to a different neurologist at UCHealth who diagnosed me with ‘chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids.’ It is one of the newer autoimmune diseases. Also called CLIPPERS. Steroids helped me immediately.
See if you can get a copy of your MRI or have it sent to major medical center or teaching hospital near you.

Mayo Clinic has a discussion group on CLIPPERS:
https://connect.mayoclinic.org/discussion/clipperslooking-to-connect-with-others/
Will you try and look for a neurologist ?