I’ve recently developed this. It doesn’t itch and it’s under my boob. Do you guys think it might be something from my bra? I’m freaking out! Help

Edit: I just changed bras cause this one didn’t fit right. Also I sweat almost daily during workouts could that also be a cause?

Edit: Intertrigo! I think I might have a skin rash from wearing the wrong bra and the moistness from me working out and letting it dry by itself when I should have been wiping it