Cramps but no period after taking pill

Back in Novemeber during the week of Thanksgiving I took a Plan B pill within 24 hours. My cycle occurs towards the end of each month and I took the pill when my period was ending. Two weeks later, I experienced light bleeding and assumed that it was from the pill. During the last week of 2009, I've been experiencing cramping. On New Years Eve I took a Next Choice pill within 3 hours. I still continue to have cramps, but my cycle isn't starting. I took the pregnancy test twice (two weeks later) and both came out negative. I haven't experienced morning sickness or sensitive breast but I'm starting to get worried. What do think could be wrong?

[melimeli]

Are you using these pills as your birth control?  it is not meant for that...

[Victoria01]

The Plan B is for emergency contraception only. It is not meant to be used regularly as it will mess with you cycle. I would go to your doctor and have them check you out and also get on a reliable form of birth control.