Keep an eye on it but maybe don't worry yet. JG's soumetimes sound a little different from other breeds. Their baby-chick "peep" moves into a "clurk" sound as they get to be a bigger chick. Your crop description is not too alarming. The crop will go up and down depending on how much they are eating & how fast it goes through the system, and much of the big bad crop problems (sour crop, impacted crop) don't really happen in chicks because of the chicks' diet. Keep an eye on the droppings. It's not that unusual for there to be a watery poo every now and again, just try and keep an eye to see if it's every poop. I wouldn't worry too much about the breathing, since there's not much you can do about it. Bigger breeds sometimes breathe heavy & it's really unnerving, but not always a sign of illness, and in a chick that old, I would not be too worried. I have a 10-lb. rooster that periodically gasps & breathes heavy - he has for years - and he's almost 5 years old! The water spit-up happens with chickens sometimes. They can't really vomit, but if they have just drank & then get stressed somehow, they may duck their heads and the water comes back out of them. Nothing to worry about.
The best indicator of health is going to be their behavior, and the fact that this chick is fighting you when you examine it is excellent news. Sick animals, including chickens, look sick - eyes half closed, tail down, not moving much, less interest in food, water, and what is going on around them. Possibly droopy wings. Sometimes their feathers look a little ruffled and raggedy as they stand there with droopy wings (this is called huddling). As long as your chick is active and not looking sick, he/she is probably doing just fine. Good Luck, and I hope this helps.
