What came out of my rats mouth? and what do i do!?

i found my rat eating some tortilla, i didn't think it would do her any harm so i let her continue to eat it, but then she drooped it and started looking like there was something stuck to her throat, she ran away and when i found her her chin was all wet and it looked like she had bubbles coming out of her mouth, there was also some mucus looking stuff of the rag were i found her. the thing is she looks okay now, she cleaned her self and looks normal now, i heard that rats cant puke so what happened to her is she sick? and can she be contagious to my other rat?