To me, it sounds like a insulin resistence (diabetic) rash, or a yeast infection due to insulin resistence, perhaps erythrasma. Losing weight will help. Failing that, antiboitcs for yeast/bacteria infections will help. Given that you are not diabetic yet, of course. Pre-diabetics, hypo, or hyper will net postive results. Full on diabetic, especially if diabeties is not controlled, you may find yourself struggling with this off and on for the rest of your life.
Best bet, if you are concerned, is get with your doctor. In fact, any kind of question like this really should be addressed with him/her.
This and
this may be of help
*Not a diabetic, not a doctor, not a nurse. Just literally everyone in my family and extended family is. How I missed the curse, who knows.*