What Causes Pain In Shoulder Radiating Towards Neck Despite Taking Tegretol?

hello I have been having pain in my right arm that is nw travelled up my shoulder neck and the top of my back my doctor gave me Tegretol Carbamazpine 200mg I found my self very hard to wake up in the morning my friend told me to ask my doctor for gabapentin I looked it up but side effects are the same what would you sugguet