What Causes Pain In Spine Radiating Towards Rib Cage?

I gave birth a year ago. For the last 6 months or so i ve been getting increasing pain in my wrist joint and thumb. Sometimes it swells up. Its really bad now. Also in the last couple of months ive been getting pain and swelling in my knees too. Finally for the last month after ive been laid in bed for a few hours a get really bad pain down my spine which seems to extend round under both sides of my ribcage making it really painful to turn over in bed. What is causing this?