Blister/sore inside vaginal opening. Pictures?

There is a small sore or something right inside my vagnial opening. This is the second time this has occured to me in the past couple months, however I went and got blood tested for SDI/STIs and everything came back normal. Does anyone have any ideas as to what this could be? I noticed this one today and started feeling it during intercorse. It does not hurt any other time except when having intercorse, putting in a tampon, etc. 

When did you perform tests for HSV after the exposure ?

I went and got tested about two weeks after the first sore type thing appeared. I have not had any new sexual partners or anything like that since then.

Did you perform a viral culture using a swab taken from the sore ?

If it got a negative result, you can be pretty much sure, you don't have Herpes.

But, I reccomend you to retest at the 6 week mark too. Bcz, it is conclusive. 

But, If you get a positive result, you from the swab, start antiviral therapy as soon as possible. 

Meantime, please visit your doctor. Getting checked by a physician is very important. 

I got the blood test done, so a swab was not taken. Results came back negative.