I agree with everything VTMorgan06 said. Start from the source, and get x-rays. My vet was even able to email me the x-rays which I then showed to my farrier — if you have this option, take it! It was priceless.
My OTTB has struggled with chronic laminitis for about two and a half years and the keys for him were a great farrier, LinPro, and Happy Hoofwear shoes.
Depending on the severity, I would generally agree with keeping a laminitic horse barefoot when possible, however, my OTTB has such thin soles that stepping on a small rock or simply getting too much footing stuck in his hoof then running on it can give him bruises and subsequent abscesses. This is where the Happy Hoofwear shoes came in really handy. They are made out of polyurethane and are flexible. I could write an essay of all the reasons I love them, but I think the main benefit in regards to laminitis was that they allowed the hoof to move, therefore promoting circulation, and making my horse’s hooves grow a lot faster. And if your horse is anything like mine, he may have large chunks of hoof wall missing from hoof resections to remove dead lamina. The Happy Hoofwear are light and my farrier was not only able to use very small nails to nail them on, but he used the clear shoes so he could more precisely see where he was putting each nail.
The thing that has probably helped my horse the most (other than my saint of a farrier) is the supplement LinPro. I always thought hooves only grew from the coronet band down. He kept growing hoof wall from the coronet band, but it wasn’t attached very well and continually cracked and broke off — leaving us back where we started. I discovered LinPro about two years into my horse’s problems, and it made a MASSIVE difference. LinPro seemed to help the hoof wall grow outward from the inside of the hoof. Like I said, I didn’t know the hoof wall could do that, but I was totally amazed at the new growth. Within a couple months, he had grown enough (sturdy!) hoof wall that he was sound, the farrier could nail into the new growth, and HE’S BEEN SOUND EVER SINCE. I’ve even started riding him lightly again over the past month. For that two years prior, he was probably only sound about a third of the time in the pasture, and only a handful of times under saddle.
Anyway, sorry for writing such a novel, but I know how frustrating it can be to try a million different tactics over long periods of time and still not have a sound horse. It sounds like yours is well on his way to recovery! Good luck