Checking cervix causes heavy bleeding

I spot every month before period and I have been trying to get pregnant for nearly 2 years for my 3rd baby. For my first 2 children I did not spot in the month I got pregnant so the way I check if I am out for the month is to check my cervix for spotting.

For the past three months when I check my cervix few days before period I suddenly bleed heavily for couple of minutes and then it resumes to normal spotting until my period starts.

I was just wondering if anyone else has experienced heavy bleeding from checking cervix and what could the cause be?

Thank you