Hi,
I'm no expert but we had sleep problems for a couple of months from this age until starting a form of PU/PD. If one tooth has arrived, from our experience, several more are close behind! Does pain medication/teething gel help?
Also, I'd recommend doing all you can to re-establish daytime naps (even just one) because he is bound to be overtired by bedtime. I don't think one will work without the other. Is there anyway to help him take a daytime nap while you concentrate on a bedtime rountine and better night sleep. Will he nap if taken for a walk or drive - just while you work on better night sleep, then you can work on independent naps?