You will know what you have been doing recently and whether there is a risk that you have picked up an STD so while you should never dismiss it if you think you may have been exposed, the symptoms are usually more severe such as discharge, open sores, and fever.
If you have been having sex, see a doctor about your problem. Your partner may be clean as far as you know but what if he/she had one little infidelity that was never mentioned. Don't be embarrassed to talk to the doctor and to get your bits out, he or she will have seen much worse.
If you have just been masturbating though, it could be the lubricant you have been using. Some men like to use types of soap but this can cause the problem you are experiencing because it removes oil from the skin. The penis is mostly muscle and stretchy skin. It needs elasticity so by removing oil, you are reducing the capacity to stretch without causing tissue damage. This is not a reason to not washing yourself. Just don't be rigorous with the soap.
If you think it's a masturbation problem, try laying off it for a month. It may be difficult but just imagine dropping your pants for a partner and her seeing your penis in its current state. Focus on the long-term gain in having a healthy looking organ.
The doctor could still be worth a visit though as he may be able to recommend creams that will sooth your penis without removing the essential oils from it. In other words, you will be masturbating again in a lesser amount of time.