Check the learning center page for links to disease lists, if you don't get an answer.
Definitely isolate her from flock - this can't be good. If she is having trouble breathing - the foamy stuff could be mucus/snot - then I would suggest putting a dab of Vicks type menthol rub under her wings where there are no feathers. I have used it often on chickens, chicks, and turkey poults with good results, and no one has ever told me it was harmful.
You might try Googling "chicken foaming at mouth" too. Their sinuses can cause their eyes to swell, ooze bubbles, etc.