Baby refusing the bottle

My 2 month old daughter is all of a sudden refusing the bottle. I breastfeed during the day and my husband gives her the bottle for night feedings. She was doing fine up until recent when we tried giving her frozen milk. She drank some but when we burped her mid way, she stopped taking it. Maybe we thought it was the frozen milk so we tried fresh milk. She initially drank it but after burping her mid way, she refused it again. Anyone have any idea why this might have happened? We tried another type of nipple and refused it. She’s definitely hungry because I would breastfeed her after trying for a while. I’m going back to work soon and I’m worried! TIA