hi, what do you give him to bring his temp down?
when my ds had a febrile convulsion we were told that in future, if he started to get a temp we should bring it down aggressively by using both the recommended amounts of paracetemol (calpol) and ibuprofen, as you can give both of these at the same time.
of course you cant do this for 3 weeks!
do you know what his "normal" temp is? its a good idea to take his temp when he is ok, so you know what is high for him. (eg. our ds normal temp is about 35.6, so even though a doc would say that if he had a temp of 37 it would be within the normal range, WE KNOW its high for him, and to take appropriate action)
apart from giving medication, we would just try and keep him cool by not having the central heating on, stripping him off to just underwear, maybe using a fan if you have it, and maybe sponging him with a cool cloth.
sorry i dont know if teething can cause a temp.
good luck. phone NHS24 if you are still worried and ask for an appt with your local out of hours doc.