You should look into square foot gardening. It's companion planting to the nth degree. Maximizing harvest by interplanting herbs with fruiting plants , and by doing that reducing weed pressure and watering. Check out gardenary on YouTube.
Its good that it doesn't smell. It could be a mating injury. See how it heals over the next couple of days. You may need to soften the scab with compresses so that it heals well. Do you have a beeswax cream at all?
Go for it! I don't know dosage for ducks, for chickens it's 250 mg twice a day for 7 to 10 days. You'll want offer yogurt with live cultures during the treatment to restore gut flora.
They aren't the best mothers. They're originally from countries in Africa where it's never damp, if you get heavy dew the keets will get chilled because she'll probably take them out into it.