What is the ruling on practicing masturbation to alleviate testicular pain resulting from prostatic congestion, given that abandoning it brings back the pain?

Masturbation is forbidden by Islamic law. What the doctor advised you is null and void and should not be heeded. The Messenger of Allah, peace and blessings be upon him, advised young people to marry if they are able, and if not, then they should fast. So, you must abandon masturbation because it is a disease, not a cure. Strive to get married, and if it is not possible, then occupy yourself with beneficial deeds in matters of religion and worldly life, fast frequently, and stay away from anything that arouses desire.