I have two ulcers on the opening of my vagina, help! (Pictures to be added)

Hello! If I could have some guidance that would be awesome.

So I recently got tested (within the last two weeks) for STDs and as did my partner so I'm confident that we are both clean. I have two ulcer like sores right before the entrance of my vagina on exact opposite sides of each other. It stings a little when I walk but theres no burning sensation when I use the restroom or anything like that. They're sort of a white color and the similarly resemble blisters. The last time we had sex we had sex about five times and the fifth time it started to be a little bit painful. Any idea what it could be? 

How do I add pictures? 

Was any force applied during intercourse by your partner?

I believe so. The pain actually started while we were having sex.