we have ky, we just didnt have it with us the last couple of times. that could be the prob.
NOT SURE IF YOU BOTH SAW MY POST AWHILE BACK ABOUT BARTHOLINS GLAND...IT CAN CAUSE PAIN...ESPECIALLY WHILE WALKING. I WILL EXPLAIN FURTHER IF YOU WOULD LIKE.
It might possibly be due to a lack of lubrication. I had a very similar problem. Then we invested in some K-Y. I have not had the problem since.
im going through the exact same thing. it started hurting after having sex but like an idiot i just had sex again so now its getting worse it hurts really bad. no idea what it is though.