That would be a really unusual place for herpes symptoms to appear. That would be way, way down my list of things to worry about.
I'd think fungal infection, friction/chafing, some kind of allergic reaction, dermatitis, etc., way before I'd think herpes.
Before you start loading all kinds of creams on it, try to narrow it down. Have you worn anything new - new shorts, pants, underwear? Maybe you're allergic to something in the waistband of one of them. Maybe there's a metal in a snap or zipper that you're allergic to, or one of those metal divot things on pockets. Maybe you can figure it out by where the symptoms are.
It could be fungal from sweating and working out.
You really should let a doctor look at it, and decide how to treat it for best results.
You posted awhile ago about bumps on or near your vagina. Did you ever get that diagnosed? This could be from the same thing - maybe a fungal infection or something that is spreading.