Originally Posted by JanM
His reaction to foods is first his skin gets an ugly red/purple colour then small sores develop - they bleed. It progresses to his body to where he will stagger and fall. His eyesight is going and when he is in a generally "bad" state, it's worse.
Unless he is suffering from severe, life-threatening malnutrition, a food allergy/ sensitivity should have no effect on his muscle strength, balance or his eyesight. Is there something else going on ?