Hallow Dear, It seems you had consumed post coital emergency contraceptive pill after the unprotected intercourse to prevent the pregnancy. These emergency contraceptive pills contain some progestational medicine as an active reagent. The withdrawal bleeding after progesterone is always lesser in amount and is associated with cramping pain in the uterus. You have experienced both; however, this is normal. Nothing is wrong. From next time you will get your menses with adequate bleeding without much of pain. I hope this resolves your query. Dr. Nishikant Shrotri