Why does it hurt everytime me and my husband have sex? I have been to see my ob many times about this problem. He also checked for std's, negative.

Dyspareunia. Pain during sex can be caused by multiple conditions. Location of the pain: vaginal superficial as opposed to deep penetration, the proximity to menses, spasms in the pelvic floor muscles and vaginal lubrication need to be evaluated. Endometriosis need to be ruled out. Consult with a gynecologist experienced in pelvic pain.
Dyspareunia. Another possibility is a condition called interstitial cystitis, a painful bladder condition. Many women have recurrent symptoms similar to a bladder infection with urgency, frequency, pelvic pain the symtoms come and go and may be confused with recurrent utis if you have recurrent bladder infection that requires multiple antibiotics to "treat" you may have ic.