my baby is 4 and 1/2 months old and today as been a hard feeding day. She seems to only eat like 2 minutes on each side then pulls off and starts crying, goes back on for a couple more second then repeats the crying. When I switch her she is fine for a couple more minutes, but then she does the same thing. It seems like it is gas, because I burp her and she farts then she seems to feel better for a little while. I was wondering if she could have heart bur or something like that because she seem to spit up a couple of time right after I feed her. She never really spit up before, so could it be acid in her tummy? And what could I do to help her?