Back Pain, kinda.

I am 19+1 currently and I have been noticing this for about a week now.

I can (usually) comfortably lay on my back or even propped up if watching tv or reading blah blah blah.

However, sometimes, I will get this pain at basically the top of my left but cheek and moving doesn’t make it go away. It makes walking uncomfortable and every other activity.

I understand just not laying on my back but it has happened while sitting as well as standing.

Any thoughts on what it might be?

TIA