My 2.5 year old has a lot of coughing. What should I do?

Hello, my son has been sick for a few days but I am very worried about his cough. He coughs so hard that he becomes red and spits until he vomits. For the last few days he has been sleeping badly at night. After physical activity (running or jumping) he coughs a lot. In the summer he had the same case, me and dad took him to the hospital and after an x-ray it was a mini pneumonia that went away with an antibiotic. A few months later the problem started. Back at the hospital, they told us it was an ear infection. Same thing; antibiotic. And now it's happening again. Is his cough now related to the flu? We are very worried that it could be something else. Thank you for your help.