My dog got lung wrom and his founding it hard to eat how can I help him

Lung worm is common in rural areas where dogs can roam; I would suggest you take your dog to the vet for medication, and keep him Inside more. The fact that he can't eat would mean the infestation has gone on too long and has progressed to his trachea. The vet will treat similar to deworming for tape or hook worm, which you will have to administer.