It's strange but I've noticed when I take my dose of antibiotics the pain get MUCH worse.
I do clench and grind my teeth at night, have for a long time. Sometimes I wake and my jaw and neck hurts so bad from it but the pain has always subsided within ten minutes. I also clench my jaw during the day and don't realized it until it starts aching.
It could be TMJ issues. You may clench at night.
Also, sometimes if I move my neck around it will click or "pop" at the base of my skull and the pain and pressure will subside for a few seconds.