I had sex without a condom two days after my period ended and took the plan B the day after i had sex and i got my period again that sunday but it only lasted until monday..is that a bad thing..could i be pregnant ?

Anon,

That second "period" you had is from the Plan B, and I suspect it was that short and light simply because you had just finished another period. In other words, that uterine lining was already very thin from having been shed during your normal period.

You should be fine. You took Plan B right away and it had the intended affect. But please do know that in many women, Plan B does cause irregularity in a woman's cycle, sometimes for a month or two. So if yours doesn't sort itself out for a little while, don't worry. It's normal.