Remedies for boob rash??

I’m sorry for the pictures

but I have bad boob rash year round never stops that my skin is getting darker it’s cause of my weight I get the pimples and cyst under them everyday my mom had gaved me some vitamin c oil that didn’t work I tried to put powder under it didn’t work it had just made it worse... my right one is sensitive when I wipe gently with the whole sweat and Bacteria building up my skin is starting to bleed a lil I don’t wear bras much only going out or going to work .... please no harsh comments please...