Thanks for the question; it seems that you are in the habit of excessive masturbation. It is possible that while masturbation you hold the penis very hard because that can a reason for the problem you are facing. It has been observed that many exert too much pressure and hold their penis very tight which causes rashes and redness. Another thing which i would suggest is to stop washing your pubic area with antiseptics, as you are having rashes and redness use just clean water for cleaning your genitals.