What Causes Cough, Gagging And Acute Breathing Sounds?

My four month old has a loud cough(multiple times in a row) immediately followed by a gagging(sometimes ) when he crys his voice is scratchy and has a hard time crying loudly , occasionally when he breaths in the sounds similar to how a person would sound when having a asthma attack. he has no fever nor a runny nose however sometimes when he s sleeping everytime he breaths in it sounds like to pieces of Velcro gently rubbing together. What could this be? And how can i sooth is cough and voice?