Yeah, I had that with another health problem last year

I had a nasty rash of some kind under my arms, but it would always disappear before I got to see the doctor

So, one day while waiting to go in, I noticed it wasn't showing up, so deliberately scratched my armpit until it was red raw, just to prove that it was real (the old doctor was still there then, a very unsympathetic, incompetent man who once refused to give me anything for bad hayfever because it was 'self inflicted'

)