I wake up every morning with a sore throat why is that?

Mouth breathing: You may breath through your mouth while you sleep, which dries out your mouth and throat. With a dry mouth, certain bacteria can proliferate which causes an odor. Try brushing your tongue as well as your teeth, and when you use mouth rinse, gargle it into the back of your throat as well.

Several possibilties: You may be a mouth breather and the physical drying of the back of the throat may be responsible for discomfort. Drink some water in the morning. Other possibilities include nasal drainage from allergy or sinus drainage producing post-nasal drainage. These symptoms need to be diagnosed properly by an ENT doctor.