Plan B discharge

Alexis
I'm going to go insane someone help!! I had sex on the 22nd(towards the end of my period) he DID use a condom but, I wasn't finished with my period until the 23rd. I took Plan B on the 24th, today I went to the restroom around 5 and had brown discharge. every time I've gone to use the restroom it's changed to red discharge it's coming out light but it wasn't there all day, please someone explain what's happening