On my placebo pill week I had unprotected sex with my boyfriend like I usually do after my period finishes. The next day on Friday which was the start of new pack which are active pills I was placed on antibiotics for falling and getting an infection on my knee. I asked the doctor if I should still take both at the same time and he said yes just use a back up method. My question is can I be pregnant because I had unprotected sex on Thursday and the next day on Friday I took both antibiotics and active pill???