Help!!

Okay ladies, I have a serious issue here. I had unprotected sex with someone on Monday. I was off birth control for 5 months and I just started taking it again this month randomly, i have been taking it at random times as well as missing a few. The guy wants me to take Plan B because he thinks I could get pregnant. My boobs are hurting SOO bad and I have right side pain. Could i still be ovulating? I don’t know what to do? could I get pregnant? Conflicted on this one and need help! Please if you think I should take the plan b or not. I really trust you guys and I appreciate every answer!