I have a rash on the crease between leg and vagina for 4 days i'm starting to cough but my brother has been sick can i have herpes?

Unlikely: Herpes usually presents as an ulcer on the genitalia themselves. What you have there is probably a contact or allergic reaction to clothing (underwear). If it persists, see a dermatologist

Rash: The rash described sounds like a superficial skin yeast infection. Cough may be a coincidental respiratory infection especially during this time of the year. Herpes lesions are usually vesicular/ fluid filled bubble like lesion. Try OTC anti fungal cream on the rash if not better see your Pcp

Herpes is a painful,: blistering,red rash.A common rash in the skin folds of the groin is a fungus known as Jock Itch or tinea cruris.This is not a sexually transmitted disease and is treated by over the counter antifungals.Best to have a doc see the rash to be sure you are not infectious.Until then,abstinence .