Worried it may be croup..

I know you guys are not doctors, but my mom doesn't seem to worried about it and is about to take a trip out of town so I won't have a vehicle if I need one..

My son has what seems to be a cold (he's had several), he's congested and has a nasty sounding cough that won't go away. Today he woke up and he will cough and then he sounds like he's losing his breath and when he's breathing in it sounds weird.. I was told before that with croup the cough sounds like a seal? I'm not sure what seals sound like, buut the sound he makes sounds like what I would think they sound like, though it's not when he coughs it's afterward..

What would you do? My mom doesn't think I should worry..