What Causes Softness And Purple Color In Cervix After Unprotected Sex?

During my check-up, my OB-GYNE mentioned that my cervix was a soft and purplish in color. My husband and I had unprotected sex during the time I ovulated. I have been experiencing abdominal cramps 12 days after and I am still experiencing them now. My breasts are also tender. I took the pregnancy test 3 times alread but the result was negative. What does this mean?