If these were mine I would cut out the concentrate completely. Then lots of branches (willow, hazel, willowherb, some ash - not too much, makes them loose, beech etc) and do they go out to graze into a field with good grass? Hay racks full o/night. Red Rockie licks for minerals. Some fruit/veg as evening treats. Nothing else and monitor if their feet improve. Have you got the possibility to weigh them?
Laminitis aside, if their feet smell you have got footrot/scald, probably both. So that needs treating with a footbath and AB's probably. No idea what treatment for laminitis would be.