I'm in the Phoenix Metro area, too.

I was referred to the (Gregory W.) Fulton Center for Neuromuscular Diseases by a Otolaryngologist that recognized the symptoms I was having.

They started me on Mestinon, and it started working, but I took a bit of a downturn after a few days, and they decided to do Plasmapharesis on me. I went in to Barrow in a wheelchair, and walked out 6 days later.

Barrow is considered one of the top Neurological institutes in the country, so you'll be in good hands.

There is a chapter of the Myasthenia Gravis Foundation of America (MGFA) that meets in Tucson and Phoenix. They're inactive over the summer, but there are people that you can call for info. The website is below.

Arizona Chapter of the Myasthenia Gravis Foundation

Good luck.