I'm not breathing properly? ?

Basically..in the past I've had fairly badly bruised lungs and stuff and I get post viral asthma from time to time....but recently (like last day or so) I don't think I'm ok :s it's like I can breathe in n out...take deep breaths etc...but I'm definitely not getting enough oxygen? Like my lungs don't feel like they're filling up like they normally do and I've been really light headed....my inhaler made no difference either? What should I do?