Yes, GERD can cause bad breath. The acid can cause chronic sore throat and you must reason that the tube of digestion is continuous from your mouth to your anus. It’s important to get your bowels moving regularly and the best way is with proper diet. If I make a smoothie with 2 tbls ground flax seed my bowels are guaranteed to move. (Must be ground ) do not consume the seeds without grinding, I use a coffee grinder. Much healthier than taking stimulants. Sugary foods, grains, processed foods are very constipating and especially ice cream.