3 Month Old Duck has Limp

I have a 3 month old duck that developed a limp today. I noticed him laying in the middle of the yard today and when I went to see what he was up to he had a limp. It looks like its his left foot, he's trying to put the weight on the right foot. He can walk but with a limp. He's enjoying his pool still but keep his foot near his body and doesn't extend it to kick with when he's in the water. Can anyone recommend anything to ease his pain or to possibly help him feel better?

Thank you very much!

This is the foot that I think is causing him to limp