Swollen ring on penis

Patient: I had a night of some rigorous dry humping (underwear on) with my girlfriend, then later that night I had masturbated. When I woke up in the morning, I had some swelling in a ring from (little less than a quarter inch wide at the top of the shaft, right below the corona of glands. Is this anything serious?

Symptoms: None, just swollen ring on Penis, does not hurt.

Doctor: