If it continues for the longer term and isn't just a matter of days it might also be worth looking up the symptoms of reflux. Reflux bubs have the pain of the acid coming back up, so do lots of feeding to try and soothe the discomfort but as they eat then they get the reflux again so it is an exhausting cycle. Even if she isn't bring up the feeds there is silent reflux where it only enters the throat and is swallowed again. Is she arching her back? Does it help to keep her upright? Hopefully it is not, as reflux is a horrible tiring experience for mother and child but something worth considering if the constant feeding persists.

Good luck not an easy experience when you have DD1 to look after too!