I really wish I knew how I hurt my back I was fine then last weekend it started and now it doesn't hurt when I sit a certain way still it's annoying

I can lay on my side and my back with no problem but sitting up in my bed, on our couch, in my freakin computer chair hurts I must have done something at work and it's driving me crazy that idk what I did since so much happens now

idk if it's the time I lifted a carton with milk in it or when one of our kids tried to leaned against my back when I was on the carpet or being in those little chairs bent over for 35 minutes cause they refuse to do small group there's so much