Period is very thick mixed with large amounts of cervical mucus. blobs come out on toilet, is painful. not clotted blood just thick. ultrasound and hpv neg last month. had this for 4 years. if cancer, would it have shown on ultrasound after 4 years?

This does not in any way suggest an increased cancer risk. Your tests are reassuring and four years is sufficient time for other problems to become apparent. Your cervix apparently produces more mucus than average (or perhaps you are simply more aware than average) but that is not abnormal.

You should be evaluated by a GYN if you have not been already to find the cause. Pl see one