hi i am a vet ech in Illinois i saw your post hope i can help.The main cuse of this type of laminitus is excessive ingestion of rich feed(carbohydrates). No wheat no corn in the diet,access to large amounts of water after feeding in draft type/lrge equine.Many horses can founder/laminitus with sweet feeds.try cutting back to oats,a very small amt. of corn,very small and watch for foul smell in the hoof wall,if he is not favoring this foot alot this sounds like the problem if not be certain when you have your farrier trim make certain he is using clean instruments a bacteria inf. can be spread from equine to equine.you can consult your vet and get an antiinflammatory,we use phenylbutazone this will help with pain.could be the farrier please check all instruments even offer to wash them,i know this is awkward but laminitus is irreversible if left untreated good luck let us know how he/she is doing.