I need advice!

I had scoliosis surgery when I was 12. I'm 18 now. My back hasn't bothered me too much for the past 6 years. I have mild pain when I'm on my feet for a long time, but nothing major...until recently. My back hurts almost constantly. It's not severe pain, but it's enough. It hurts right between my shoulder blades, on either side of my spine all up and down my back, and *especially* my lower back. My hips and my knees hurt as well, but I don't know if that's related. I was just wondering if anyone knew the cause of my pain and what I could do to relieve it. Any help whatsoever would be very much appreciated! Thank you :)