9 week old choking on saliva in sleep

The night before last the most terrifying thing happened. Our 9 week old was asleep in her bassinet, swaddled on her back, and i woke up at 1 to hear her almost gurgling. I turned on the light and her eyes were wide open, terrified. There were bubbles of spit coming out of her mouth. She was wiggling back and fourth arching her back not making any noise. I grabbed her and patted her back pretty hard and i thought she couldnt breath. I stuck my fingers in her mouth to see if she was choking on anything, and her jaw was so tightly shut. Im not sure if i handled this the right way. I had my husband call 911 while i kept patting her back and trying to get her to take a breath and come to. After what felt like forever (but in reality was only a minute or 2) she came to and started scream crying. The emts came and checked her over and she was completely fine, she even smiled at them. She was content and calm after this. The next night i stayed up and just like clockwork, the same thing happened again at 1. This time i was a bit more calm and i rolled her over on her side but she still seemed like she couldnt catch her breath so i grabbed her and bent her over and patted her back. It lasted about 2 minutes again. After this, she was fine again. Does anyone know what this is? It is so scary when it happens and i can tell it freaks her out. I dont think it is reflux, as she is breastfed has never been a gassy baby, nor does she spit up or burp much. She does hiccup sometimes but its pretty mild. This happened well after i fed her, about 4-5 hours. She has started drooling like crazy just in the last week, which i think could be related, but i thought they cant choke on their saliva. Has this happened to anyone else? Do you know how/why it happens? What can i do to help her in the event that it happens again? We ordered an owlet sock but it wont be here for 3 more days.we took her to a chiropractor a while ago and she said her jaw was tight and she has been having a bit of trouble breast feeding but she is perfectly healthy and average weight for her age. She may have a lip tie but we havent been able to get her assessed for that properly yet. We took her to the doctor but got shrugged off. She laughed and made a joke about me being a new mom. Any help would be greatly appreciated, i havent slept since it happened and im an anxious mess.