Have i got the herpes simplex virus or something else if pain only the first time i saw blisters down there?

Possibly: From your brief description it most likely is herpes. Other causes could be irritation from shaving or waxing, "diaper rash" type irriation, pimples, or other vaginal lesions. Observation by your physician should be as soon as possible so he can diagnose and treat the problem asap.

Rash down there: There is no way to tell. You need to see your dermatologist. He or she may order a blood test to look for evidence of herpetic infection, but even that is no substitute for visual evidence.