?

Hi all. I had a question. My girlfriend has been on birth control for awhile. She is pretty good at taking it everyday. About 2 weeks ago, she was diagnosed with strep throat, so the doctor prescribed her Amoxicillin, where she was taking about 1-2 Amoxicllin pills per day. She was on Amoxicllin for about a week and a half, when we had sex. After having sex, we realized and found out that Amoxicillin CAN alter the effectiveness of birth control. When she realized this, we started to panic so she went in the next morning to purchase Plan B emergency birth control pills and took both pills that morning. She is still currently taking her birth control pills now. I am very paranoid about her being pregnant. If I could get somebody's opinion, I would really appreciate it. Thank you!