Please help me! I have a question about birth control. Very Urgent.?

I have been taking Yasmin (birth control) for 1 month and 3 weeks to be exact. Just the other day, but I dont remember when, I took an allergy pill. I was just told today that if you take cold medicine or allergy medicine, there is something in them both that can mess up my birth control like i wasnt even taking them at all. i just had yesterday. what are the chances i will get pregnant? if it only for the day that i take the allergy medicine that it will mess it up, does anyone know how long the allergy medicine will wear off. somebody please help me, i couldnt find anything on the internet or with the instructions my pills came with.