Modafinil substitute

I’ve been using modafinil for the past month. Sometimes I have a strange feeling on the left side of my chest which doesn’t bother me, but I’d like to make an appointment with my gp and see if I can use some other form of medication which I won’t feel this side effect. Modafinil does work for me as I am more aware in the afternoon, whereas before I always felt tired in work. Can you recommend something else as my gp seems a bit clueless regarding ms.