The actual frostbite doesn't look too bad. I have to agree with Chicken thief, because it looks like there might be something else going on! I've never seen a chicken swell up quite so much from frostbite alone.
It is possible he may have an infection setting in. Almost looks like there is something going on with his chin there too. That seems to be where most of the swelling is concentrated. If you wanted to make an appointment with your vet, that would probably be your best bet. I really think that something else is going on that we can't see from the outside.
If you have some terramycin on hand, you could start him on some of that. Watch to see if the swelling comes down at all. Sometimes the wattles will swell up when the frostbite is healing or about ready to fall off, but your vet may need to actually open up his chin and drain that out. It's possible that he might even have an absess.
Definitely dose him with some plain aspirin. I can imagine he would be in pain! And let me know how this turns out! Now I'm very interested to see what happens!