Birth control and antibiotics

Patient: Hi there, i have been on the birth control pill for about 4 years now, i started on yasmin but was switched then switched again to tri cyclen and now i am on seasonale, as of today i started the last week (sunday). However i was siagnosed with pnemonia on feb 17th and was perscribed antibiotics i took them the same day perscribed. My boyfriend and i had unprotected sex on feb 20th he did not pull out and i started expereiencing discomfort in my lower abdomen, nausea and bleeding on feb 24th and has lasted 3 days so far (the bleeding). is there a possibility that i could be pregnant?