What Causes Right Leg Swelling And Mid-back Pain After Spinal Fusion Surgery?

in 1992 I had a disc fusion.... L4 and L5. The left leg has always been smaller than the right leg since that surgery. Actually the right leg appears swollen. The past 4 months I have been experiencing a shocking hot fire sensation ...lower left side of back... starts under bra area and goes down to hip. I also can't cough without pain in the middle of my spine under the bra area. The middle of my back feels like it is breaking... so I go from laying down to sitting to standing because I can't do any of those things without pain. My toes are turning numb while I sleep. I am very fatigued all the time.
Medications I take now are prozac, synthroid, advair.