Pain after sex! 😣 advice please!

I need advice please!!

I recently started having sex 3 months ago (I am a 19, and a female having sex with a guy) and when we first started having sex, I had cramps afterwards that lasted 24-48 hours afterwards. They went away for a little while but over the past 2 months I have been having cramps again. But I have also started bleeding for like 4-7 days at a time. It feels like a normal period except I have been bleeding for like 20 non consecutive days this months (photo as down below) the first line was my normal period and everything else has been chaos.

I have the bar in my arm as my form of birth control and I don’t know if this has anything to do with the bleeding, but I need to someone to tell me if they have had a serious experience and whether I should go the doctor.

Thanks