If he's not dreadfully upset I wouldn't do anything, Naomi. Just lots of cuddles and something to chew on. Natty's teeth didn't give us any trouble when they were coming through, so I'm not really experienced, but I've heard people say that their babies chew on a wet washer... Though that's probably older babies I guess.
Personally, I wouldn't go for teething gels unless bubs was really upset... and even then they often don't work. Not sure about the amber necklaces - I have heard them spoken of around here but I don't know anything about them. Hope he's his happy little self again soon.