I was also thinking it could be a herx symptom. I know I have random nerve issues, where a bit of pressure creates a lot more pain than it should. It should go away in a little while with some good detoxing - but if it doesn't, watch for redness & swelling around the nail. It could be an ingrown toenail (no fun!!) or some other infection. Soaking with Epsom salts is good for those things too though.