I heard from a doctor site that this is where their is skin folds,.. Basically where a part of skin is folded OF COURSE =P. Under the buttcheek, boobs, lady parts, and under arms..
If it's on your Inner Thigh I'd say its probably a boil..
Get medicated powder, not baby powder, or scented powder because it may make it worse..Powder your inner thighs down, and also that part of your pants when your slide them on.. So instead of your legs rubbin together its the powder that rubs..
When your legs rub it makes friction, and friction is heat,..An if your legs touch then the heat has no where to go, instead of releasing itself into the other side of your leg. Wah la, bump.. -It happends to me too!-
Now for under the boobs, under arms, buttcheek areas.. I get painful sores there too, also where my bra maybe rubbing me.
I heard if you get out of the shower, and try sitting out with a hair dryer on cool/cold, and put it over your body in the creased skin actually helps pull the extra moisture out of your skin where the sweat, or dirt or whatever else has no water to build up on, and basically "hurt you with"
But if you cant air dry, patting yourself down with a towel is the next best thing.
-And you will learn that hydrocortisone cream is your new best friend.
Sitting in a hot bathtub, with sea salt in it for about 30 minutes helps as well -Geez dont mind my spelling though, Long night at work w/o sleep lol..
I do hope this helps...Its some of my home remedies my mother, grandmother, and I do.