my girlfriend feels vaginal discomfort after she cums.

One day, my girlfriend and I were making out, and I started to finger her. She enjoyed it, with moans, deep breathing, and she tells me what to do. I rub her clit, or finger her with 1 or 2 fingers, and she feels no pain while I do this unless i get too rough. Then after she cums, she say's she feels a stinging sensation in her vagina, and around her clit, and I can see that shes in ALOT of pain, she has to sit a certain way and can't move for awhile, usually about 20 to 30 minutes.

We didn't know what was wrong, maybe I went too rough? So 2 weeks later, I fingered her again, trying to be as gentle as I can be, using only 1 finger, and rubbing her slowly. She came, and experienced the same feeling. She doesn't want to go to her parents and ask about it, were only 16. So we waited 3 months before I fingered her again, and she's still experienceing this feeling. Am I doing anything wrong? Do I need to use lubricant?

I've talked to her about letting me go down on her and just using my mouth, but she isn't ready for it yet so i'm not going to pressure her. We've been together for 10 months now, and I really want her to experience and orgasm without any pain.