Mast Cell Activation Syndrome: What treatments help you?

I was diagnosed with MCAs about 4 years ago. Since being diagnosed
I have received multiple treatments that either never worked or worked for a short period of time. My symptoms are pretty severe including hives, high blood pressure, Low Vitamin D3, memory loss, brain fog, sweating, flushing, Chronic diarrhea, stomach bloating , etc...
I have been treated with Xolair injections that seems to help for about 7 months until my body began to reject it. I have also tried Chromium. I take multiple anti-histamine daily with little to no effect.
I currently live in Los Angeles and finding a doctor that specializes in MCAS is almost impossible.
I was wondering if the MAYO Clinic in Arizona has any doctors that specialize in the treatment of MCAS.

Best regards, Robert