Hi, I have a rash under my armpit, it s flat with a few bumps, the entire pit is hyperpigmented since the rash and the flat area is tender and red and recently started to have a foul smell, which is not as bad as rotting flesh as some persons have described but it s not a sweaty odour for sure. It is not oozing but it feels, dry and scaly to the touch and it has an irritable sensation rather it itches or not. What can this be, it is only under my left pit; right pit shows no symptoms.