duck swollen head

[Chickensrule69]

i own Indian runner ducks and today i noticed one of them off by itself and all alone. At first i was scared thinking something got my other duck because my runners always stay together but then i found the other duck and its head was swelled up.I have never owned ducks this is my first time. I have researched them a bunch and i have gave them all the vitamins they have needed they also get a duck feed and fresh water daily. Can someone help me out? The last photo is them together you can see one’s head is more swelled than the others. Maybe i’m just worried over nothing. But there was also a little blood. I thought maybe the duck just scratched its head.

 

[Miss Lydia]

Possibly a wasp or hornet sting? Have you looked under her feathers around her neck and head for any type of bite even snake?
Is she able to eat a nd drink?

 

[Sondraa]

What happened with your duck? Is he ok now? Please advise the issue when you get a chance.