Baby chokes on saliva

Kamryn
I was about to go to sleep and I have my baby next to me in a bassinet and she was asleep. Well right when I was about to close my eyes. She starts chocking on her spit. I mean when I say choking this poor little hopeless baby is struggling to breath making squeaks. I of corse jump up right away and pick her up and start patting her on the back to help clear an airwave. Then she stops choking and she's moving her mouth like there was something in it. Like she was chewing on something. But it was only bubbly saliva. No spit up.
 I'm only breastfeeding. And she doesn't spit up much. The only time she spits up is when I believe she eats to much. I'm just so scared to put her back in her bed! Cuz if I were to go to sleep and she chokes again and I don't hear her. Oh man. My head is going everywhere right now.  This is the first time she's done this in her sleep. 
Has anyone gone through this? Baby girl is 5 weeks young.