my best advice is for you to find some more stuff to engage yourself in, and more positive distractions. your reports were fine from the doctor which is a good start

if it gets worse, by all means go back and explain to them what it feels like and ask for the tests again

but my guess it's just a bit of health anxiety.. you think about the pain and all the things that people can have go wrong with their backs and think well, what if that's me

anxiety can do strange things to the brain (including thinking you have pain when you don't). I'm often in the hospital for fake heart attacks, for example- my brain thinks i'm having a heart attack, but actually I'm fine