I had cough and flu, then I couldn't breath properly and my chest tightness. If I took a breath, I could hear a sound in my chest. What was that?

It sounds like. It probably was something referred to as "wheezing". This a breathing sound that is often heard in "asthmatics" but also can be heard in people with acute respiratory illnesses that lead to reactive airways disease(sort of like asthma). If you are still hearing this sound see your doc.
Cough. Most likely the infection when down into the bronchials (breathing tubes). This could be bronchitis or if the infection gets into the lung tissue itself it would be pneumonia. If you are having trouble breathing you should see your physician. They may need to give you medicine to help open up the airways.
May be bronchitis. Cough and flu can cause your mucus glands to produce mucus. This can lead to inflammation of your airways or bronchitis. Please check with your primary doc. Get well.