I have been experiencing pain in my teeth/gums, what could this be?

The past few nights (possibly? I’m not even sure exactly but I know I have felt this a few times in the past week or so), I have been feeling this pain in my bottom and top back teeth. It’s not like a sensitive pain, it’s just annoying and I guess can just be described as a toothache, but it’s all over & on both sides. What could be causing this? I have never had a cavity (22 years and going strong) or braces, and was at the dentist just about 6 months ago. I don’t have the time or insurance to go to the dentist any time soon… so hopefully this will pass. I am just curious as to whether any of you have had similar experiences.