Suggest Treatment For Difficulty In Moving Left Arm

I lost the use of my left thumb and finger next to my thumb, a few years ago, i am now having problems with the grip in my hand, and cannot move my left arm properly, i have tried rubbing cream on it but not stopping any pain i gat in my arm, i have been to my doctors and getting no help, they just give me cream to rub on but not helping, can you please advice me thank you