I suggest that you visit your gynecologist to get a professional opinion. Inflammation of the cervix, vaginal infections, Uterus fibroids, & much more can cause pain. http://www.webmd.com/sexual-conditions/guide/female-pain-during-sex
If you have already been to see your gynecologist, what did he say?
How long is your husbands penis? Many women complain of pain when it is longer than normal.
Another excellent option is to visit Dr. Betty's website that has a great discussion group for women & their sexual problems: http://dodsonandross.com/