Heel pain

I am 50 yrs. old and have suffered from heel pain (only left foot) for about 10 years. It has been steadily getting worse. I had Guillian Barre Syndrome in 1986 and it affected my left side more than my right. It started in my left foot, which is where I have the pain. I have had 2 surgeries for the pain; one to release the Plantar Fascia and the other to remove scar tissue as a result of the first surgery. Each time I had the surgeries, my foot felt better for about 3 months, then it all started again. I most recently had a laser procedure done on my heel, wherein the laser was supposed to destroy the bad tissue and new, heathy tissue would replace it. It did not work at all for me. I also recently had a cortizone shot (the first one I've ever had), and it helped me for about 5 wks. When that time was over, the pain came back with even more vengence. I now have a blood blister on the bottom of my heel, which, my podiatrist just told me, was because of the pressure of me walking on my heel. I am not overweight and I am perfectly healthy otherwise. I take Cytomel for thyroid and that's all. I wear heel pads in my shoes. Any suggestions???