I went through something like that..

..and assumed it was the mattress, so what I did was rotate the mattress 180 degrees for a few nights.. 180 degrees so that the left/right side you normally sleep on is on the other left/right side of the bed.. My reasoning was that, over time, the mattress had "caved in" for lack of better words, where I slept, causing a dip that crewed my back up.. Definitely turned out to be the problem - in my case - and got a new mattress..

It was weird - I'd wake up and my back was in excruciating pain.. I'm, like, how did I sleep long enough in that much pain to cause this issue? Oh well.. worked out well by getting a new mattress..

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Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..