baby restless and fussy during feedings

linlee1

My baby is 4 weeks old and we are suddenly having trouble feeding her. We have been using similac complete and avent bottles since she was born.  She has always ate with no problems.  For the last few days, she has started biting the bottle nipple and is constantly moving when we are trying to feed her. It takes quite a while to get her to latch on to the bottle.  Once we get her to start eating, she screams and cries when we take it away to burp her. Then it starts all over again.  Outside of feeding time, she is a very happy and calm baby.  Any ideas what is suddenly causing this?