during sex, pelvic infection
, cervical polyp
, old endometrial tissue, etc are the other possible causes of bleeding after sex.
Withdrawal effect of birth control pill and hormonal imbalance may cause light bleeding or spotting as you stop taking them 2 weeks ago. As you finished your period 1 wk ago, then pregnancy
is quite unlike in this case.
If bleeding does not stop automatically within 3-4 days, then you must consult with your gynecologist for pelvic examination and next line management.
You can take tranexamic acid
group of medication to arrest bleeding for temporary purpose. Maintain genital hygiene. Good luck.