hi, i am 21 yrs old and my period came on 4 days early this month and lasted a day longer, now i am spotting .my bf and i had sex a week before my period, but i went to the er a day after my period started for severe cramps, and they gave me preg. test. both were neg. i was wondering is there a chance i may b pregnant, and the spotting is coming from implantation.