I have sfn since May, two months after the maderna vaccine 2nd dose. I have hot and ice cold feet and legs but the symptoms got better with gabapentin but symptoms still exist. I take 600 mg at night which helps the symptoms and helps me sleep. I'm 75 and it gives me minor balance issues and some constipation but that's better than not sleeping due to the symptoms which are worse at night. Hope you find relief. Gabapentin is what is usually prescribed.