G.M.
Yes you can experience wheezing while breathing in. When my son had croup, one of his symptoms was "strider"....that's when he was wheezing and it was associated with the croup cough and it is a dangerous symptom that can lead to hospitalization. I don't want to scare you, I'm just saying that's what happened with my son. In order to help open him up, the nurse may advise you to come in to the pedi's office to have your little one checked. It sounds from your description that he really needs to be seen by the doc. The doc may give you what's called a 'nebulizer' with some meds to use with it in order to help your son breath. The nebulizer really helped my son when he was real sick.
I hope he feels better. Right now what you're doing at home is great, but you may need the additional help with a nebulizer. Ask your pedi about this ok. :-) Hope this helps.