This may be tmi but since I've taken up running , underneath my boobs where my bra sits occasionally gets red and itchy. Got advice on here, fungal (yuk) so bought cream from pharmacy. Would normally put on for about a week and it calms it down slowly.
The other morning , at the gym, I was getting changed and I felt the tell tale itch. I was going straight to work and hadn't got the cream. In my gym bag I have a little bottle of tea tree oil that I put on a toenail (god I sound so gross with all this) I put a couple of drops on my finger pads, smoothed it over both hands and rubbed under my boobs.
The rash went in one day! I cannot believe it. Just thought I'd share this awesome news!