Hello~I don't think using vinegar to wipe the area is a good idea, it is an acid and could make the area worse. I would try using Neosporin on the area for a few days, if it continues or gets worse, then definitely see your physician.
I would avoid hydrogen peroxide, it damages tissue. Maybe you have a yeast infection. If you do, jock itch medication will work on it, but your best option is probably to go to the doctor and find out for sure what it is. You could also try over-the-counter Neosporin or bacitracin.