That's a sinus infection. Pick up the duck and press on the swollen part--you will see snot come out of it's nostrils. You need to get ahold of Baytril in tablet form. It's one of the best thing for ducks with sinus infections!!! It looks like a call duck, right? So, if so, you can give a half a tablet 2x a day for 5-7 days. Good luck!