I have a four and a half month old breastfed baby girl. She has been getting bottles several tiems per week since she was born. But in the las t couple monthor ao, she is backsliding. She is still drinking, but she acts real fussy about it - squealing while it's in her mouth, chewing on it, sticking her fingers in her mouth with the nipples, etc. She is not cutting teeth yet. I have just chalked it up to her being older and smarter - she prefers the "real thing" and is annoyed about the bottle. She is also much more distractable now, even when nursing.
I guess that doesn't really help you, but I think it might be an explanation? I sort of remember my four year old going through a similar phase around now before she took a cup.
I try to get other people to give her the bottle, since my presence seems to make it worse. I also wait her out until she is a little hungrier than normal so she is really motivated to eat. If I have to give the bottle, I sit her on my lap, upright and facing away from me so it is unlike nursing. My plan is to introduce the sippy cup as soon as I can (I still think the bottle works well enough for now, but plan to start a cup with her solid feedings).
Good luck.