PLAN B OR NOT?

So I just recently got my birth control implant out of my arm because it was more trouble than helpful. I have pretty much been bleeding every day for a few month and the bleeding stopped a few days after removal. Last night I had unprotected sex because I forgot I got it out. I realized in the middle of it so he pulled out. He wasn’t close to coming at that point yet but I’m still nervous. I’m in college and I don’t need a child lol. I’m not on any birth control now, so my only option is a Plan B. Should I take it? Years ago I took a birth control pill and it make me very sick, throwing up and stuff so Im worried this will do the same. What do I do? What should I expect if I take the pill?