For the past two nights now I've laid down in bed just to feel like I have to gasp for air just to get enough oxygen. my chest feels heavy and it's uncomfortable. I've never had this happen before so what could it be from? Can't be from eating too much or anything like that because it's been several hours since I've eaten. Also I took a nap earlier today but didn't have this problem. Any ideas? I'm 19 years years old if that helps at all...thanks