I'm happy to find this page; it verifies what I thought happened to me after my flu shot. I had it a couple of months ago, after not having had one for decades. No problem with the injection site, but 2 days later my neck and right sciatica started to hurt - to the point that certain movements were extremely painful. I am 72 and have never had a sciatica problem in my life. EVER. I work out at CrossFit, which is pretty hard stuff. No pains from that. The pain left my right sciatica and went to my left, which is improving with PT. My neck pain goes back and forth from one side to the other, across my upper back and shoulders. I am in physical therapy after seeing a physiatrist. Both the physiatrist and PT seemed to be very familiar with this type of reaction. I've been researching online, and have found many rare cases like mine. My assumption was, because of the time frame, and because of never having had anything like this before - that my immune system was triggered by the flu shot and was reacting. I found exactly this online, saying that it can attack your joints. I hope that you all update us with your progress. If you haven't been to a PT, find a very good one, and do the stretching exercises they give you at home. Good luck to us all!