My cat is sufferring from bronchopneumonia

It has been a month since my cat, Hiro Nakamura , started suffering from bronchopneumonia. It started soon after he came back home from a pet shop. He stayed at there only for 2 days. I thought it was an ordinary flu, maybe he just tried to adapt the new condition. Then I went to a vet, Hiro was diagnosed suffering from bronchopneumonia. 2 weeks after taking the medicine , hiro was brought back to vet again because of his health kept going down.But unfortunately, he ran away from the vet. Everyone helped me to find Hiro, and he was found after a week of his dissappearing (It was about 3 days ago). He was so poor, thin, and a lot of snots over his nose. When I brought him home, he always asked for food. But, no matter how much and how many kinds of foods I gave to him, he just couldn't eat! Something wrong with the tongue I guess, maybe he has stomatitis. And now, Hiro has been hospitalized for 2 days.. I really hope that Hiro will be better soon .. Anyone has the same experience as mine? Please share the story, and I really need some advices in this case