Plan b help

Ok so exactly 5 days ago I took plan b I have had no symptoms, today I'm getting the poopie cramps I get for period poops and I just sat down on the toilet and had a little blood spill out. Can't tell if this is a period or spotting because all of my periods start out light. Anyone else had this? Last period was 2 almost 3 weeks ago
Let me add this: It might be my period because I've been a total bitch this morning and I noticed it earlier. I'm never a bitch when I'm in disneyworld but I am today.