The skin you are talking about is plain old skin,
with no special properties other than looking beautiful. There are no ear-parts under it nor any other special organ. So what you have there is just a possible side-of-head trauma that dented his skin.
A seven foot fall onto a hard surface usually injures the iguana significantly. Normally they lose big parts of their tails. You have to make that 7 foot drop inaccessible, or you have to lay 4 inch thick foam on the "landing zone".
But, is he still shaking? Has he eaten nothing at all until this post? Have you not seen him drink?
If so, I would suspect there is some chance of a head/neck knocking injury, or a concussion-like injury somehow, with maybe a broken front leg.
I've seen at least several swollen gum lines, on my own and in pics sent here. The skin bulges out from the smooth jawline. That is caused by broken teeth which get imbedded in the gums. But it would be very good if you could get x-rays to check for a broken jaw. The teeth break off when the iguana bites down on something hard or brittle, like thick wire, or a rock. The broken teeth could also be a result of the seeming side of his head trauma hat he had. Swollen gums from embedded teeth usually heal on their own, but I've had to use a vet to make sure one or two of these cases got under control.
If I had to bet on it, I would bet your iguana will get well on his own. But it's safer to see a vet. I can't see anything from here. I want him to get head and shoulder x-rays.
Watch him very closely until you travel around the world to get to a reptile vet. Look for changes in behavior. If he get more depressed, it's probably an emergency.