Overuse injury (arm weakness)?

hello, over the summer i used my arm alot. like playing basketball, video games. thats all i did all summer. but one day, i was playin basketball and i felt a sudden weakness on my dominant arm. it didnt hurt. it was weak. the next day my right arm (dominant arm) became weaker. and weaker the next day. i rested my arm for about 2 months. no playin bball nothin. and i still didnt get 100% on my right arm yet. its not a serious injury or anythin. but its still weak. i play basketball and i shoot with my right. im worried.i didnt tear my muscle or anythin. (mage therapist said so.) she said i just used it too much and i damaged soft tissue muscle around my right side of my back. i think thats from sittin on a little chair playin video games for a long period of time, and thats why blood wasnt really flowin to my right arm. my back was also tingling. the mage therapist just felt that i had this injury right when she touched my back. u think my arm is goin to fully heal?? thank you.