My 5 week old has gained 2lb since birth and seems to be getting what she needs. However, sometimes she becomes very irritable while on the breast. She cries, screams, and throws herself back to unlatch herself but then quickly tries to relatch and keeps on sucking. This goes on, back and forth, throughout the feeding sometimes. Then she sometimes looks like she’s in pain afterward. I’ve been taking it to mean she’s gassy but is this normal? Could it be something else? Perhaps reflux?