I burns...oh does it burn

So I just turned 24 and my lovely body gifted me with my first UTI 🖕🏻👍🏻

So went to the doctors today and she asked about birth control etc. I told her no..I was trying to get pregnant. She put me on macrobid and told me I need to have a back up birth control method for the rest of the month... any idea why?

Yes I know I should have asked but I got off work at 6am waited 3 hours for the doctor to open then sat for an hour..ya girl has to be back at work in 8 hours so I basically ran outta that joint.