Hindsight: Riley has scratches AND something else

Ri has an ailment. Shocker.

I took Ri to a show Sunday, and we competed despite a pesky swelling in his left hind that started about five days earlier on July 5. After a dry spell, we had strong t-storm cells move through  overnight, and Ri came in the next morning with a "big leg." I thought he had been stepped on by Harv in the thunder (which was very, very loud and close). But that was not it. He was not lame, once the swelling subsided (exercise brought the swelling down to near normal). It's not an abscess -- at least it doesn't seem like one at this point.

Guesses? Anyone?

Scratches. We think. There is a pink area behind his pastern, a little scabby, and it's very tender. My best guess is that he had some dry skin behind there, maybe a little cracking with the very dry spell we've had until July 4.  The night of July 4, it rained/thundered, and I think maybe some sort of fungus or bacteria took hold in the compromised skin. Opportunistic infection? Ri's hooves also seemed to go to hell that night, his right front is flaking up again.

My vet has him on SMZs and a mixture of Desitin and Neosporin applied to his dry, clean pastern.  She's concerned about cellulitis.

Update 7/12/12. So, I was out yesterday afternoon to do my three-hour horse nurse stint, Riley and Harv, and noticed something on Ri's RIGHT hind above the fetlock, like a hen's egg. Looks like a wind puff, but with sudden onset, AND it's a bit more "turgid" than a windpuff (not squishy) -- though clearly a moveable fluid --  it may be a bit warm, and Ri is ever-so-slightly reactive when I press it, although it's hard to say since it is exactly where you press to get him to pick up his foot. The footing at the last show was damnably deep....