I Was Assaulted 10 Days Ago By A Friend Of

I was assaulted 10 days ago by a friend of mine and there was no penetration but he touched himself then kept touching my vagina. I took plan B within the recommended time. A few days ago I started light bleeding like I do before I get my period. Yesterday it seemed it would turn into a regular period because it was coming out pretty well but after awhile it just turned into brown type bleeding that is only there when I wipe for the bathroom (been having this bleeding for about 3 days now). I have been extremely traumatized by this experience and just wondering if that sounds normal for how Plan B works or if I should be scared to death that I could be pregnant given the circumstances.