First and foremost. Stop riding him as long as he is limping AT ALL. Until you eliminate all possible reasons for lameness his lameness riding him at all is likely not in his best interest. You may be causing the continuation of something that needs other treatment beyond just thrush. Has a vet seen him yet?
Next, correct trimming (whether in shoes or barefoot) is essential for treating and preventing thrush, and a lot of abscesses as well. Pictures of his feet my help advise you better in that regard. Oncw the feet are trimmed and.pr
shod correctly then whatever commercial or natural thrush remedy you want to use will be much more effective. I personally pack the infected central sulcis with a special absorbent cloth material ("foot felt") that only absorbs non water based liquids and just keep the packing saturated with Thrush Buster.
Oakum (a farrier fiber hoof packing) used in the central sulcis for packing can work, too. Or if there is a marine supply near you, 'boat bilge oil absorbing felt sheets' are the same thing as foot felt. Only a lot cheaper.
One sheet from a boat supply is a few bucks and will last one horse forever because you only use teeny little strips. .