I had never heard of it either. It started overnight but I totally think it's related to the vax. Even more, I think it possibly started after the first vax as my neck bothered me all summer, so much that I bought 4 new pillows, one $149 to relieve my neck. My first vax was May 4. These are awful months of waiting. I had googled my symptoms and FINALLY asked my fam doc to do blood work for RA. I even asked for blood work at the ER. That's when they found out my CRP levels were way too high. So now I wait for the neurologist to get back from Christmas vacation. I hope you're doing better now. I hope I will be doing better after I start Prednisone (if).