yes, as pp said, it could be your baby has reflux.
ours each had reflux & showed different symptoms (one not eating, the other trying to soothe the discomfort w/ more). we started on zantac, but had no real success until we progressed to zegerid. just in case you do get a diagnosis of reflux, i highly recommend checking out the marci-kids.com and the infantreflux.org sites for info on proper dosing for your child and *then* take her to the doc - printouts in hand. one of the peds we had (after we moved) needed the info from those sites because at first he refused to prescribe in a different manner than what he had before with other reflux medications; he knew nothing about zegerid. (and yes, zegerid was *awesome stuff* and totally worth the effort!)
p.s. the doctor may tell you to add rice cereal to thicken the feeds. *please* see this page for info ("what about thickened feeds?" & decide for yourself whether it's something to try for your baby:
http://www.kellymom.com/babyconcerns/reflux.html#thickene...
also, if you can afford it, it can be quite helpful to just assume your baby has mspi and give her nutramigen. give it a couple of weeks if you can & see if it makes a difference to switch back. it did with our firstborn & put us in a position to be able to figure out almost all his intolerances/allergies before he was even 10 months old (which i was told no test can do as effectively, or even before 12 months, btw.)
hth & best wishes for you guys! :]