Can Antibiotics Decrease The Effect Of Birth Control Pills?

About 2.5 weeks ago I started on yaz birth control. 2 days ago I had a bad rash so I took 2 prednisone 20mg that day and 2 yesterday. I had sex last night without a condom, and he pulled out but some still came out inside me. Now I am worried because I have heard that some antibiotics decrease the effectiveness of birth control. What should I do?