My main concern is the spot on the lungs, I don't understand why the vet is not exploring this further. Any spots on the lungs whether infection or tumor are quite serious and need to be diagnosed. Because there is redness (I assume it lasts a few days not a quick, short reaction) and fever, infection of some kind might be going on. Does he go outside at all? Has he been checked for immune related viruses like FeLV and FIV? In the short term I would probably try to boost the immune system (good food, perhaps some supplements). Also if describe in more detail (kinds of discharges, times of day more current symptoms, other inconsistancies that reflect his heath at the moment), perhaps some remedy suggestions may follow.