Throbbing pain that is most severe in the evening on the top and bottom of my mouth. It’s moveable, and it changes positions, from the back-centre, to the far back.
I have a tooth that needs a crown. I was able to get a check up that diagnosed this but not for the work to be done due to covid. 
However- this tooth does not hurt at all. I can bite on it, press it- and it is completely painless despite the surface decay.
None of my teeth actually hurt. I can eat, brush my teeth and have a good poke around with no pain whatsoever- it is just the gums. Sometimes I can feel the throbbing in my cheek.
I am struggling to get an appointment due to Christmas and covid naturally. Is there anything I can buy over the counter?
Any ideas what this pain might be?