make your own Colloidal Silver and have him to drink that for water. offer that and water and let him self medicate and see what he does.
additional potassium Iodine is a good idea. i would start with one drop (30mg) or maybe dilute SSKI half and half with water and one drop would be 15mg or so per day and go from there. selenium too. about 20mcg selenomethionine a day. chop a tablet or dispense from a capsule 100mcg five ways and at the end of five days you know the whole thing has been taken.
nutrient rich food. feed him glands and organs and such.