I have had a small lump right under my jaw all the way in the back where the jaw ends for about a week. it does not really hurt. what should i do?

Possibly sublingual : You have lymph nodes throughout your body to protect you from infections. Some can be felt through the surface of the skin. Those are in the front and sides of the neck, the back and sides of the neck, underneath your tongue, in your groin. You can look in an anatomy book. As the infection goes away the nodes slowly shrink. For more assurance see your doc!!