Reflux or Food Intolerance?

My baby is constantly SO fussy. She spits up a lot, often curdled milk. After feedings she strains like crazy. I don't think she's constipated; she has regular bowel movements and they are always a normal consistency. I don't know if she's having trouble passing gas or what. Gas drops haven't seemed to help, neither has gripe water. I'm going to start cutting foods out of my diet starting with dairy, but does anyone have any other tips? Might it be reflux, or something else? I'm calling the pediatrician tomorrow, just looking for advice.