question: I have a pain in the lower left side of my back. The pain becomes worse when I sit down suddenly or go to the bathroom. When I sit down to start to go to the bathroom it s a quick sharp pain that causes me to bend over and then slowly eases into a dull ache. I thought it might be built up gas, as if I was constipated, but I m not and the pain has been going on for a few days now.