5mo refusing bottle??

my 5 mo is starting to refuse bottles??? when i'm around i nurse him exclusively but obviously when im at work he has to take a bottle... i've been back to work almost 3 months now & from what my mom & husband have told me usually the first bottle of the day was rough but then the others get better.. well apparently suddenly he's only drinking like 2oz each feed & only with a ton of push back from him.. has anyone else experienced this at this age? or have any advice for me?? i'm stressed.. obviously he's not gonna starve but he'll surely be cranky...