I think she could be pregnant. First, she stopped taking birth control. So when she resumed it, she had to give it a certain amount of time before it was effective again. (I'm assuming that she was on the Pill since you didn't state what kind of birth control she was using.) Then, since she took antibiotics, that lessens the effectiveness of birth control.

It would really depends on whether or not you've been using back up methods like condoms... have you?

well considering she did stop the pill for a few weeks, i think it was a mixture of that and possibly the meds. remember, antibiotics lessen the effectiveness of birth control. so if you two had unprotected sex during this off time or the time she was on it with the antibiotics, she could be pregnant. but if you guys were safe and used a condom, then i think it was just that time off. tell her she doesnt need to take time off of the pill. if she was moody it could be that brand of pill just wasnt right for her? she should just contact her doctor, maybe get a different prescription. but you dont need a break from the pill.