Hi there,  Im 20 yrs old i had my period last January 3 to January 8 ..and last January 10 (2days- after my period),  i had a sex with my bf but he didn't ejaculate inside me.. But now January 14 (4days after)  , im shocked cause im bleeding again i feel tired, my boobs somehow feels sensitive,  lower back pain and lightly lower abdominal pain.. What should i do?  Am i pregnant?? Or is there something wrong with me?? Can it be also cause by stress???  

Please help me... Thank you