birth control pill and antibiotic

I was on the birth control pill but also on an antibiotic at the same time. I started my period early and me and my boyfriend had unprotected sex on July 8th. My period was only for 3 days and I was a virgin before I had sex wih him. I've been getting sick for the last 5 almost 6 weeks, I can't eat most of my favortie foods without getting sick. I have also been having pains in my lower back, my brests, my hips, and in my lower stomach. I'm almost 3 weeks late on my period and can't hold my medication down. Could I be pregnant?