Sharp pain on lower left side of abdomen, should I go to the doctor?

[Megan]

I've had this really intense pain on my lower left side of my back, sort of by my hip bone and kidney, for about a week now. It appeared really suddenly and I thought it would go away in time but it's only gotten worse. I press on the afflicted area and it doesn't hurt any worse, but it does hurt when I move around and especially when I walk. It's really freaking me out and I need to know what it could be, how I can fix it, and if I need to go to the doctor. Please help.