Breathing Troubles @ 9 Weeks & 5 days

I had a scary sleep episode last night. I woke up feeling like all of my oxygen had been sucked out of me. It was extremely frightening, and it took me over 15 mins to completely catch my breath, and start breathing normally again. I have seasonal asthma, and it was a different feeling than having an asthma attack. Since I am overweight, I have been tested for sleep apnea before, (including during my last pregnancy), and the doctor doesn't think I have it. This is the first time something like this has happened to me, and I'm honestly worried about going to sleep tonight. Has anyone else had something like this happen to them? Any advice on methods to improve breathing during sleep?