Boob sweat (in between my boobs)???

My boob sweat stinks and I tried applying deodorant like you guys suggested but it didn't help, in fact i had a dark mark running down in between my boobs for a couple of weeks after I tried this. Prior to this year, I had never had a sweat problem but this year not only did I start sweating under my arms but I also started getting stinky boob sweat. I used to be able to let my SO suck on them whenever but now I'm so self conscious about the boob sweat that I don't let him till I've secretly sussed it out and made sure there's nothing there :(