Duckling has yolk sac outside it's body

[Chick and duck mom]

Hi. New to all this. My mama duck went broody and had no eggs. I was lucky to find some locally. It's been over 30 days. Today my drake pulled her out of her nest box and was trying to mate but being mean so I hosed him. I've tried candling but could see nothing. Somehow one of the eggs got out of the duck house and was laying in the pen with it's shell broken. Since I thought I had no ducklings I put it in a plastic bag. Something told me to look again. I opened it up, basically curious and found a whole formed duckling inside. I thought it was dead, but then it opened it's eyes and moved. Tried to put it back in the nest, but mama wouldn't accept it. Yolk sac is on the outside. I have it in a towel in a plastic box and have the heat lamp on it. Basically sleeping, but will peep if touched. I feel awful that I interfered, but want it to survive. I wouldn't have interfered if I had known there was anything inside. Does anyone have any suggestions. I did put Vaseline on the sac to keep it from drying. Thank you

 

[nuthatched]

Just let it absorb and try to keep it restrained.