I overmasturbate is it a health problem ?

Define "over": You didn't say what you meant by "overmasturbate." at you age, once or twice a day would not be unusual, and is harmless. Other than chafing of the skin, there's no physical harm you can do by masturbating frequently. However, if you think this becoming a compulsion rather than just a way to deal with normal arousal, then you may want to talk to a doctor or counselor.