Can you post a picture?
I don't know what it could be, but I can give you some things to do that are mandatory for a sick chicken.
Don't turn her upside down any more. It's good that you found the fluid coming out (if it's an indication of anything; sometimes they just fill their crops up with water and it will all come out very easily), but don't do it again because it is hard for them to breathe in this position.
Separate her from the flock.
Keep her warm and relaxed. Take her into the house if you need to. It may help to put her in a blanket-lined open container so that it seems like a nest that she can nestle into. It may also help to cover the container with a blanket to make her feel safer.
Keep her calm.
Give her the choice of water and food. You can give her her normal food. Other good foods and liquids are yogurt, cooked egg, greens, sugar water, calcium (oyster shell), and electrolytes (Gatorade). If she is up to eating, she will know what she needs. Just give her normal water, her food, and some egg and see what else she's interested in.
Keep in mind that it may be nothing at all. Sometimes chickens can fool us. If it's nothing, then the squatting is just puberty setting in, and the liquid is probably just water. She may look down because of just laying her first egg and because of puberty. If that's just it, then she will be sleepy tonight and fine tomorrow.
Hope she's OK!
