I hope Emmett is feeling better, but in your post in TAO, it sounds like Asthma. Please, please, please take him to the doctor! When my dd was 3, she had a bad cold and had a bad asthma attack. We had no idea she had asthma. I called the doctor in the middle of the night because she was having difficulty breathing and was given very bad advice by the nurse on call: to keep her at home and come see the doctor in the morning. I'm getting all worked up just writing this even though it was 6 years ago. My dd became worse and could have died. It was an awful, awful experience. We found out later that she actually saw her guardian angel.
I should have ignored the nurse and just taken her to the ER in the middle of the night. Anyway, she recovered, thank God, but I've learned to take Asthma very seriously. Do you have a nebulizer? These work better than a simple inhaler. Happily, dd's asthma seems to be better. She hasn't needed to use the nebulizer in almost 2 years, and hasn't been on steroids for 5 years, but we always keep an inhaler handy.