Found a nasty rash on my scrotum some weeks ago. Googled it; looked like a syphilitic chancre. Aargh...!
Only it it wasn't. I cut myself shaving and skin bacteria got into the wound. Cleared itself up in a week so, by the time the clap clinic told me all tests were negative, I was better anyway.
On doctor's suggestion I took the Hepatits B vaccine course. Rimming is a great way to get Hepatits B. It is. Something I absolutely do not do, but you never know if the WG has rimmed a previous punter.