What Causes Bilateral Knee Pain, Blood In Stool, Arm And Back Pain?

I have had severe bilateral knee pain for 10 years now. Had MRI of knees with nothing showing on the results. I started having severe blood in my stool about 2 years ago, with the look of it as a bright red and filling the toilet with blood. Recently I have started having arm and hand pain with numbness an tingling along with weakness. I noticed my low back starting to cause more pain that usual while my wife tried massaging it and it was very tender down low of my pain. Any suggestions?