Night attack, one duckling left, breathing funny

[princessmama]

Last night something got into the pen with our mama muscovy and eight ducklings.

Mama and one duckling are left. We brought the duckling inside and he seemed fine at first. My nine yr old cuddled him for a while and he settled right down.

But now he is sitting in a brooder and is breathing with a squeaking, wheezing sound. I think he squeeze through the fence(he was outside this morning) and that is why he is still here. Could he have internal injuries though? Is there anything I can do for him??