Hen Making Squawking With Every Breath

I have a 4 month old Cornish Cross (i know, i know, we lost a Roo the other day at 12 pounds - didn't know what they were when we got them but have tried to just let them free range eat mostly to keep them alive as long as possible) that "seems" to have something stuck in her throat, maybe. She was making a terrible squawk yesterday with every in-breath and would occasionally "cough" loudly and shake her head. I thought she was having a heart attack, as we lost one of our remaining 5 day before yesterday due to massive size and possibly heat combined. Yesterday this hen was doing the above, but would drink a lot of water as well. Today seems a little better and she ate some watermelon, but is still squawking on the in-breath - although somewhat quieter.

Any ideas on what it might be or how to fix it? Her rump is kind of black, but then they tend to like laying down in damp soil to keep cool so i can't tell much by that. Not sure what else y'all might need to know so feel free to ask away. The heat has been unbearable here in SC at 94+ lately, but they have cool fresh water available and lots of shade both in and outside the barn.

Thanks