What Causes Belching After Being On Pacemaker?

my mom had a pacemaker put in 5 days ago, she feels like she needs to belch but can t. she had low sodium meatloaf, mash potato, caulf, and applesauce for supper and takes reflux med 1hr before bed and warfarin at bedtime; is there anything she can do to calm this down. thanks for your input. worried daughter