i would ask for an ultrasound as well.. i had an etopic pregnancy which caused what i thought was my period but it was ongoing.. with only a few days in between. do u have any weird pains? or is ur spotting mis coloured?? or... if u r on birth control pills, if the horomones arent enough it will cause bleeding troughout the month, sometimes because ur new to them, or sometimes because the are strong enough.
I would have them do an ultrasound to check for ovarian cysts, which can give the same symptoms of pregnancy.
Good luck, and I hope you feel better soon!!