i need some assistance :/

i recently found out that i was was pregnant through a pregnancy test which was really faint, my boyfriend could hardly see it and had doubts but my girlfriends all said that it was def positive. tonight, i had brown blood along with cramps and i have no clue if its my actual period and i wasnt pregnant to begin with or if im miscarrying. so far, i know its normal to be cramping while pregnant but along with bleeding? kind of worried. im almost 18 and have no clue what to do. i plan on getting a blood test this week to check hCG levels etc. so if anyone could help me asap that would be appreciated.