You would think, given the size of the thing, I would have noticed it before it became so large, but... I was getting dressed yesterday and I thought it was my knicker elastic cutting in. Had a look, and there in my groin is this huge red spot. It is slightly larger in circumference that a one p piece and is the shape of a small volcano. It is very red, but has not come to a head. I have hot wet clothed it a couple of times, and have cobbled up a dressing (very awkward area). This morning, the base of it has elongated. (Viewing it properly means lying legs akimbo and using a mirror and a torch; very elegant!). Dr Google says they only need medical attention if they are much bigger than this (like 2 inch circumference) and/or you feel unwell, which I don't. Would you bother a gp or nurse with this, or would you wait and see?
Sadly, google (and common sense) tell me not to try and pop it, but if it ripens, it might be too much to resist...