Dead skin between my boobs?

Lexy

Now I'm a clean person, I should just about everyday. Body wash, the whole nine yards. But I hav big boobs, so wearing a tight bra all day I suppose build up of dirt and dead skin build up between them. Like when I shower I scratch at it and it comes off under my nails.

The point I'm trying to make is there any girly hacks to get rid of it better? Bc sometimes I don't get it all and it just looks nasty