Uhilun, I'm confused. Is this a hurt chicken or a hurt guinea? Your post title says "Hurt Chicken", but then later you say she's a guinea hen. Two different species, not related, not interchangeable.
If she's a guinea, and sleeping in the trees, I don't think there's anything you can do but cross your fingers and hope for the best, unless you can trap her in a coop or enclosure during the daytime, and then wait for dark to complete the capture. I have both chickens and guineas, I know how hard it can be to catch a guinea. They are masters of evasion.
If she's a chicken, but moving so fast you can't catch her, I wouldn't worry too much.
In case you do catch her, whatever species she is, I've used Bag Balm, the stuff that comes in the square green tins, on extremely severe wounds, and had the hens heal up fine, even grow feather back where the skin and some flesh had been torn completely off, and on deep gashes. As long as the bird isn't too shocky to recover, (and yours obviously isn't, she's running and getting up in the trees ) and there are no organs damaged, it's amazing what they can recover from. When mine get hurt like that, I clean them as best I can with warm saline, which I make by boiling water with 1 tsp. sea salt per pint, and letting it cool to about body temp. If there are areas with caked dirt, I put a cloth soaked with saline on it to soak for a few minutes, but if it doesn't come off easliy, I leave it. Pulling something like that off can cause a lot more harm than good. I pat them as dry as I can with a clean cloth, or gauze if I have it, and slather on the bag balm, very thickly. I reapply bag balm as needed until I judge that she doesn't need it anymore, when the wounds are dry and scabbed over, not oozing. I keep the bird confined separate from the others until I think she'll be ok.
