Baby Refusing Bottle

My boy just turned 3 months and he suddenly seems to be fussy whenever we give him bottle. He has been mixed fed bottle and breastfeed with formula and bm since he was a week old. Has always been ok till recently. I've also changed the teats to a faster flow one. Have been using Dr Brown's and Avent bottles. But still he's fussy when given bottle. He's ok when breastfed. Has anyone experienced this? I only have heard of baby preferring bottle over breast over time but mine seems to be the opposite. How can I make him want bottle again? I'll be gg to work in 2 months' time.#pleasehelp #1stimemom