Masturbation is not harmful to health.In fact it relieves you from tension ,you can masturbate once in three to four days. Any habbit over in excess is not good for health. Overmasturbation causes fatigue, insomnia, premature ejaculation, erectile dysfunction,testicular pain etc... Avoid overmasturbation . Try to divert mind , hang out with friends, develop good habits , play gamed, read books, take away guilt from your. mind ,be positive have healthy nutritious foods, do exercise ,yoga. And hairfall and boils on the scalp are not related to masturbation. Consult with a dermatologist for that.