Baby Won't Eat Anymore

My 5 week old is breast and formula fed since I do not produce enough milk. He's been taking Gerber Good Start Gentle just fine. My doctor gave me samples of Enfamil and mistakenly I only put that in the diaper bag to go to a family get together. I gave him 1 oz after a feeding and he seemed fussy but I thought it was because he was overly tired, he was awake for a long stretch just before. I tried a another 1 oz bottle later in the evening and he was refusing it. Since we got home last night to his regular formula he will not take a bottle AT ALL. I know he's hungry because I don't produce enough milk but he screams if I try to give him a bottle now. 😢 How do I fix this and get him to eat?