I agree with the suggestions from above. I have a mare that fought with thrush for 2 years even though I was obsessively vigilant - her problem was just the angle the farriers were using (I went through 3 before I got one I liked) was wrong. I know that wasn't your issue, but you would be amazed at what wonders a good trim at the right angles will do. There are some great websites where you can read more about barefoot and the advantages of going barefoot. I wanted to see the profile to see if the angle was off, and it looks like it is a bit. You can add a biotin supplement while you're waiting for the new hoof to grow out - it helps LOADS.
Try out Home of Swedish Hoof School they have lots of info (LOL a swedish site too ha ha!!)
Barefoot for Soundness
Welcome to Ironfree Hoof
There are tons of others, but those 3 are my faves, and they have lots of pics between the 3 of them.