Musicians with Dystonia Bulletin Board

For a guitarist, finger designation for the right hand is (from the thumb to the ring finger) P, I, M, A, for palmar, index, middle and annular (ring) finger. I've tried everything to keep the index finger from extending when doing a MAMAMA trill or just alternating, but nothing works yet. There's no pain associated with it, only the frustration of not being able to play like I used to.