Interstitial Cystitis (IC) Support Group
Interstitial Cystitis (IC) is a urinary bladder disease of unknown cause characterised by pelvic and intense bladder pain, urinary frequency (as often as every 10 minutes), and pain with urination. It is not unusual for patients to experience nocturia and pain with sexual intercourse. IC is also known as painful bladder syndrome (PBS), particularly outside of the USA.
Try lubercation something natural. If you go on the Interstitial Cystitis network they have some products for IC and sex.
Also letting your partner know about your pain and taking it easy helps. Some women use ice afterward or heating pad.