I have never heard of a brain infection related to Gilenya … perhaps the doctor was referring to
Tysabri, although a doctor should know the difference.
Tysabri also may be worth a try. Yes, it has shortcomings, but like Gilenya, many people tolerate it well and have good results.
I don’t know anything about gabapentin, other than that it is not a disease-modifying drug interchangable with Gilenya, Tysabri, Copaxone, Avonex, Rebif, and Betaseron.