Having Sore, Dry Flaky Skin At The Tip Of The Penis After Masturbation. Cause?

I Masturbate at very random times. half of the time i have little to no sexual arousal to speak of, but ,mainly in the morning, i force myself to continue on as if i m addicted. Since When I Get A Good Orgasm I Want To Feel It Again Within Hours Or After A Nights Sleep. Although A Distinct Feeling Of Drain Occurs After My Intitial good Orgasm I m a 22 year old male. I Almost Always Masturbate Through My Pants Either In A Stroking Manner Or Ontop Of A Blanket Thrusting My Hips On Top Of A Concrete Floor. I Am Quite Vigurous. Within The Last Couple Weeks I Got Two Sores On The Tip Of My Penis which seem to have white dry flaky skin around the latestest sore. The First Is Almost Healed, And Neither Had Any Symptoms before Just Raw Looking Skin. I Think This Happened BeforeOnce A Couple Months Ago. I Have Been celibate For A Year And A Half And I Had An STD Test About A Year Ago Showing I Am Disease Free. What s Wrong With Me Am I Masturbating Too Much Or Unhealthfully?