My Mouth Sometimes Feels 'full' With A Tendency To Bite

My mouth sometimes feels 'full' with a tendency to bite my left cheek. And if I lie flat on my back the ends of words such as 'didn't', 'couldn't', 'politician' get 'stuck' almost as if I have a cold but I certainly haven't. In the mornings I feel as if there is phlegm at the back of my throat and I feel I have to keep clearing it but here is no phlegm.