After masturbation three weeks ago I got little burning sensation on my penis tip. No pain while urination. No discharge. But a little burning sensation is sometime during the whole day. I done urine test for STI which were negative. I also did IGM 1 and 2 for herpes. It came as negative or non reactive. Little redness and little bit swelling over meatus on one side. But no pain during urination. Burning is more after masturbation and penile head becomes slightly red. I showed to doctor he gave mi 3mix cream and told me nothing to worry about. But still slight burning sensation is der. What is it? Is it thrush? Or balanitis? I am very worried and scared to death. Please help mi doctor. I am afraid that it will make me impotent. Please please help me doctor.