Go have the foot he's lame on x-rayed. If your close to UC Davis you have one of teh best equine hospitals in teh country at your disposal. However they aren't cheap. You might also find a vet that works on racehorses. Those horses are worth a lot of money and the owners wouldn't take them to a vet that didn't know about lameness and there isn't any kind of lameness that a vet like that wouldn't have seen. I would either spend the money and get it taken care of right NOW or I'd put the horse down. I wouldn't make him stay lame for any longer.
You don't have to put him down and I think it is wrong of your trianer to say quit putting money into him and put him down. Unless he is in severe pain I don't see why he needs to be put down. Otherwise if there is no luck with all the things mentioned above, If you are in a position to keep him as a pature pet would be nice. Then you arnt loosing him. How old is he?
He's only 12 and I'm not in a position to keep him as a pasture pet, we are at the cheapest place around and their pastures arnt flat and still cost a good deal of money. I won't be putting him down unless its certainly the last choice, I don't wanna get rid of him at all.
Did they do a nerve block on the lame foot to see what effect that has? My guess would be navicular in BOTH front feet. One reason that he may not be limping on one foot is because both feet are causing him pain. A horse can only limp on one foot at a time. I ended up buying a horse that had this same problem and the owner had taken it and had it denerved and the horse was sound for several years after that.