What Causes Bleeding And Abdominal Pain After Having Sex?

i am 21 years old. i shared some physical moments with my bf 2 days back. during which we almost kind off had matting but am not yet sure about it. post which almost half an hour later i had blood stains and am having a lil bit pain on left side of my abdomen. can i be pregnant? n how to confirm dat i m or not or not taking the risk i shall take contraceptive pill? n is there any harm of taking the pill?