Excellent advise from Excited. I'd suggest she see her gynecologist to have tests done and maybe get a recommendation for a specialist if needed. But is she willing to do other fun things to satisfy you (blowjob, handjob, etc)? Is she possibly afraid to tell you what really turns her on because she thinks you might not like it?
But, if she's not willing to discuss her problems or desires, help satisfy your needs, or doesn't want to see a doctor there might be other relationship issues you two will need to seriously discuss. Good luck and I hope it works out for you.