Lynda, I have this all the time. Same as you - good when I wake up and then it gets worse as the day progresses. It does feel swollen at times and hurts. All my bottom molars hurt sometimes too. Mine is only on the bottom left side - also the roof of my mouth on that side gets tender sometimes too.
I got all of this when I got Lyme Disease. I am sure I now have osteoarthritis in my jaw joints. I got it in my fingers when I got Lyme too.
Good luck - you are not alone!