I'm full of questions today. :(

I'm 30 weeks. I woke up last night and I had rolled on my back...& I felt really short of breath. That's never happened before and I wake up on my back quite a bit. It's happened two other times today when I was laying on the couch on my back. Just now I had to get up and catch my breath and go outside to the cool air because I felt like I was suffocating. I'm fine now...should I call L&D or wait for my dr office to open up in the morning?