I had spinal fusion l5-s1 last October. I went to this doctor as he did it minimaly invasive. Somethings are better but went and had CT mylegram 3 weeks ago and still hurts when a I walk. Gave me a SI shot as he thought it could be sacroiliitis, the pain went away for a few days and now is back. I know I am older , but used to run around 25 miles a week and now can only ride the bike as it does not hurt when I do that. Any thoughts or ideas?