Firstly - don't panic. Okay, seems impossible I know.
I'm going through a similar thing at the moment. I went to my doctor who did a load of swabs to check for infection - all negative. Also did a pregnancy test (highly unlikely since i have a mirena coil) - negative. Still happening so I went back. She made an urgent referral to gynecology. The doctor says my cervix looks fine however given I've previously had CIN2 removed and they didn't spot that until I'd asked them to bring my smear forward because I was bleeding after sex and again all other tests were negative.
You should go and see your doctor. And be persistant. My doctor says that bleeding after sex is always a sign that something isnt right. It may not be CC, in fact there are many more problems that could cause this symptom, but it should always be investigated.
And once you've been seen you'll feel better about things.