I'm glad you had a better appointment and interaction with the doctor. I too am surprised she mentioned the expensive ultra sound but no mention of ANY testing to find the cause.

Did she at least increase the gaba to something other then once a day, so you get better coverage?

Also, did she have a cap on the dose of gapa that she'll go to before quitting?

I'd say give this (and her) a try. At the next visit you can bring up the subject again about testing (like skin biopsy). She may have a different opinion that day.