Your son might have shingles and not fibro. I had a rash on my ankles for months before it broke out on my lower back and was diagnosed as shingles. The pain was terrible. Please see a doctor immediately and mention shingles to them. If they say people don't get shingles on their ankles, don't believe it. I had terrible shingles blisters all over my foot, and I am still suffering from nerve damage in my foot. This isn't something to wait around for. See to it immediately!!!