I am a 22 year old boy once while playing cricket I stepped on a manhole and had a fall which gave a jerk on my left upper arm it was 2 years ago I consulted with my local doctor who said it is a muscle sprain but even today at some angle there is a cramp like thing on my backside of upper arm during cramp it pains immensely but cramp is only for 20 to 30 second but it pains in that area for 2-3 days and again if I try to stretch my hand backwards above head and try to rotate it gets cramp i.e when I stretch my hand at back side there is a sudden pain for 20-30 second in my upper arm at the top of my upper arm on the back side it is like the same feeling of cramp in legs it is only at certain angle I can move my arm but there is some pain the cramp occurs when I take my arm overhead and backside is there any serious condition or will exercise may resolve it.