Hello , I understand your concern. I am Dr. Arun Tank, infectious disease specialist, answering your concern. Masturbation never causes any problem to the penis or health. If you do it with dirty hand than you can have bump on penis. I suspect that you have done it with dirty hand so that you are having bump. Cold therapy on penis can cause scar. This scar will now take a long time to get cured. I advice you to wait for a period. Do not get stressed with the situation. Take the healing procedure to take its time. Meanwhile you can practice the masturbation but with clean hand and with open pant. There are many false belief of the masturbation in the peoples mind. Actually masturbation never causes any health problems. In fact it can relieve the mental stress of yours. I will be happy to answer your further concern you can contact me here or you can contact me on bit.ly/DrArun We wish you a best health at healthcare magic. You can hit thank you button if you are helped. Thank you, Dr. Arun Tank If you are satisfied with my answer rate me as five star and close the answer.