My female Khaki just injured herself about a week and a half ago. Same deal, wouldn't bear weight, didn't look broken, no bleeding. I think she just got it caught on something. Anyway, I did call the vet but decided to watch her for a few days and confine her to a small area. (Which wasn't easy as she has six ducklings!). After a few days she was still limping but her gait was considerably better. I decided to let her and her brood back out to free range. After about a week there was no noticeable limp at all.
I find my ducks are way more resilient than my chickens. They're never ill and seem to get over minor injuries on their own. Good luck with your exam, but if there is not a lot of swelling, nothing looks obviously broken, or no cuts etc. I'd just confine and watch for a few days.
Disclaimer! I'm not a vet! Just my own experiences.
Edited by beccaWA - 6/2/16 at 7:15pm