Menstrual Cycle

Tay
My cycle has been regular since 2009 , I'm not on nor have I ever been on any type of birth control. I have missed my cycle and the pregnancy test came up negative... I thought when I went back an looked at it the next day there was a faint positive line. I have still be having all my normal symptoms for my cycle an don't think I'm prego but what could this mean ?!