When having sex for the first time in a couple months i bleed and then after it stops. what could be wrong?

Can be normal: This could be a "normal" thing. But if it continues, then you should be examined to make sure there is not a problem causing the bleeding.

Cervicitis STD HPV?: Bleeding after sex often is a sign of an abnormality of the cervix, such as cervicitis (often due to STDs like gonorrhea, chlamydia, or trichomonas), HPV-related cellular abnormalities, and other possibilities. All unxplained vaginal bleeding should be professionally evaluated. See a doctor or clinic soon. For expert, lifestyle-sensitive care, consider one of UK's excellent NHS GUM clinics.