I know there are a lot of people on the forum who are more experienced than I am but since no one has jumped in yet perhaps I can give it a try.
I too have battled thrush and have done pretty much the same as you except.....I would not recommend stall rest. One key to success is movement......getting the blood circulating through the hoof.
I also followed a strict routine of picking the hooves, scrubbing with a stiff brush using water with a squirt of anti-bacterial dish soap (Dawn), rinsing, spraying with a mixture of TeaTreeOil and ACV, and also I did a treatment of an anti-biotic that is used for cows who have mastitis.
Another thing to consider is how his heels are. Are they contracted? Getting them down and back will help open up the frog so there isn't a deep narrow crevice there that encourages thrush growth.
I know nothing about supplements but have added ground flax seeds to his diet and the hoof horn has grown out tighter.......along with the added bonus of a nice shiney coat
I hope this helps a bit and gets others talking. Take care and all the best to your horsey!