I think my period started?

So I took plan b 2 weeks ago. I was supposed to start my period today. I've been having super light pink discharge when I wipe for the past two days. And today I was having sex with my boyfriend and I just started to bleed. But the bleeding stopped right after. I'm not sure if that was a period or not? I haven't bled ever since. Is this a normal side effect? I still get random episodes of feeling dizzy, light headed, nauseous ever since taking the pill. I have never taken the pill before and need some advice. Thank you!