Here's an update:
On Tuesday, I had the farrier out to check on things. She confirmed my thoughts that it was an abcess. She did some work with the hoof knife and the hoof tester. While she didn't find the abcess exactly, she narrowed down the location where she thought it was. It may be too deep right now for her to open it up. Told us to keep soaking (in really hot water) with epsom salts and iodine. I give 1 gram of bute once per day after the soaking. That way if there is pain while I'm poking and prodding at his foot, he'll still show his pain and still feel a little better afterwards.
So yesterday he was walking a little better on that foot, actually putting weight on it whereas Tueday he was really walking around on three legs. Poor guy!
Did I tell you....I love my farrier! She made a special trip to my place just to check on this horse and she didn't charge me....and she hopped in her truck and was down the driveway before I could give her any cash! She'll be back in a couple weeks for a regularly scheduled visit and will definitely be getting a very large tip!
And, did I tell you...I love this horse! He's a 2 1/2 year old QH gelding that is just a trooper. This whole week he has been awesome to work with. He was brought into my husband's shop where we heat up the wood stove & watch tv while he stands quietly eating hay with his foot in a bucket....and there's no need to tie him because he stays where we put him! He doesn't care about all the strange noises, the dogs running underneath him, or the dang bucket of water that seems to always get in the way. Too bad he isn't mine! (and he's for sale....hint hint!)