Oh, poor Oliver, it must be painful. I think Redhedd's suggestion sounds good, and he keeps licking it, you better take him to the vet.

When you get burned, it takes a lot of time before the pain goes away. I once burned my finger on the oven and had to sit with it in a glass of water for about two hours. I was also burned very bad on e time and ended up in hospital for 5 weeks, there they said the best is to stay in cool water - not ice cold and not running water, for as long as it takes.

Hope Oliver will feel better soon!