HELP!!!!

I have an almost 4 month old Pit Bull that I rescued. He stays in the garage when I am at work and spends his time with me when I am at home. We go for walks and he is socialized. He is somewhat destructive but getting better as the days go by. I would keep him in a crate but he likes to destroy his teeth on the gate. So I decided to keep him in the garage free of anything that could harm him during the day. The thing is he has a reoccuring case of ear infection. 2 days after his medication was finished, I noticed his ear looking red, moist, and shinny on the inside. People keep on telling me to take him to the vet but I just spent 300 dollars on a vet bill for him for the ear infection 10 days ago. He also has a case of shedding and dandruff. He eats the finest dog food free of allergens such as corn or beef. It is a lamb, chicken, and rice formula sometimes green tripe is added. I am wondering if it is because I keep him in the garage. Maybe he needs to stay in the sun or allowed more fresh air. I don't know what to do.