Hello, i am 21 years old. i had my period 2 weeks ago and started passing blood clots yesterday afternoon. it only happens when i go to the restroom-?

Vaginal bleeding: Even though it only happens when you visit the toilet, probably the blood is from your vagina. There are many possible causes: hormonal, pregnancy related, infection like an STD, and others -- really can't even guess without knowing more. Some cases are serious, and it sounds like your bleeding is heavy; and new or abnormal vaginal bleeding always needs professional care. See your doctor ASAP.