Dactacort does a similar job as Canistewn HCl and doesn't colour the skin in my experience. There is a cream over the counter, or an ointment from the doctor. The ointment works better but causes grease marks on clothes and sticks to hair.
Check for rubbing seams on tops and bras. Without wanting to fuel the beasts discussion above, I find bras which are more like normal bras (lift and separate) allow air to circulate more than the compression type. And showering as soon as possible, or at least changing out of sweaty kit.
If it is fungal, washing kit as hot as it will cope with will help.