your partner may be pressing or pushing on your cervix and that should not happen another possibility is cervical cancer
Best to get examed by a gyno or ask your dr. There could be internal bleeding or injury, other more serious problems. Our bodies give us signs...we need to listen. Drs are going to be able to help you with this better than over the computer.
Please see your dr. then let us know how it turns out. You can help others at the same time.
Cheerz, C
Could be irritating your cervix during intercourse, it's quite common. Take it easy the next time!