baby makes strange noises and looks uncomfortable

Jennifer

Hi my baby is 4 wks old and when she is lying on her back she makes grunting noises and raised her legs looking uncomfortable. we feed her sitting up and keep her upright for at least 30 minutes after her feed. she seems to get sick a lot .... I'm wondering could it be silent reflux? this only happens at night time and tbh I'm exhausted as I can't sleep when she seems so unhappy.She was born at 34wks3days