Is it possible to have fungus on your penis? I don't know what it was? I googled and searched for what it could be, nothing seemed to match up. This is regarding my boyfriend of 3years. Immediately I thought that it could be an STD or maybe herpes? I've o

It sure is! Fungal infections of the penis are common. Also, a number of skin conditions other than fungus can cause similar rashes. In fact, most skin problems of the penis are not herpes or other STDs, just conditions that can occur anywhere on the body but sometimes on the genitals. None of these looks like herpes either. If his doc is confident in the diagnosis, you and your boyfriend needn't worry.
You . You are correct in thinking that it may be fungal. Jock itch aka tinea cruris aka ringworm can present just as you described. An over the counter anti-fungal cream like Clotrimazole should clear it right up in about 7-14 days if used twice a day. If this does not work then he should see a doctor for evaluation. The reason it cleared up before is over time the body will eventually clears itself of the infection, however this is not a good way to deal with the fungus because prior to that happening it can lead to a permanent change in the skin color of the affected area, and a secondary bacterial skin infection can develop. Please tell him this is very common with very simple treatment. Good luck.