I had similar symptoms a couple of times. A lot of pain and soreness on the left side of my neck right below my hairline and behind my ear, radiating from that location and severe headache, exhaustion, nausea, body aches and pains. It went away in a day or so. I noticed a small lump/nodule in the area that I'd had for years went down 80%. It was a swollen lymph node. I have a mouthful of amalgum fillings and I think the junk that I'm detoxing, due to the location, is probably mercury. Just sharing in case it might be something you're dealing with.