Why did this happpen???

My girl is 5 months old, she's almost 6 months old. She has slept in her crib since she was 3 months old no problem ever. Last night every time I would go to lay her down in her crib she would scream and cry. And I don't necessarily believe in the cry-it-out method but when I would just let her lay there and cry for maybe three minutes to see if she would put herself back to sleep she would choke on her saliva cuz she was crying so hard and I would have to use a nose sucker. She has two bottom teeth already. Was she doing this because she is teething? Why did this happen this happen this went on for like 4 hours and was really hard to deal with. Especially since i wake uo at 6 am to go to work.