Poor guy Ace he is a very nice looking horse, I don't see any outward wounds or signs on his legs either. I think you are right to call your farrier out as he is not putting weight on his heal. Is there any heat in his hoof at all?
Could he have stepped on a nail or screw from the downed fence or gate? While he may not have hurt himself knocking over the fence and gate, it is very possible he stepped on it after it was knocked down and shoved a nail, screw or even just a sliver in the soft part of his hoof or frog near the heal. A rusty nail would be hard to see. Have you tried washing, cleaning or picking out his hoof at all. Of course you can wait for the farrier and mention it to him so he can look for a foriegn object as well. But it may take a X-ray to see.