thank you for your query.
Penicillin would not affect you.
Bleeding while having sex is a cause of concern.
It could be due to cervical polyps, growths or erosions.
Endometrial polyps, growths also could cause such presentation.
Also, the pelvic pain
after sex could point towards endometriosis
etc could be because of the throat infection
or penicillin but not the bleeding and pain.
Please consult a gynecologist for post coital bleeding and pain.