Try feeding him in a bouncer, or lying against a pillow kind of propped up and distract him with a toy. Also try walking around while feeding him. DS was a bottle refuser for months and he did really well eating in a bouncer. Almost like he didn't want to be held and had to be distracted.
You say you are traveling...that can throw babies off. Also rule out a sore throat or something like that if this is a new thing. Good luck it's rough i know too well!!