Hi azhenhouse,
I think your duck needs something today or you might lose her, if you wait till Monday to call the vet. The only product I know that you can run out and buy that will kill aspergillus mold, that also will have no side effects for your duck regardless of what it has, is the nanosilver solution like Silver Biotics, or a good colloidal silver solution like Sovereign Silver (available at The Vitamin Shoppe). Here's a page from wildpro website re aspergillosis infection:
http://wildpro.twycrosszoo.org/S/00dis/FungalAlgal/Aspergillosis.htm
Your duck also will need to eat...one thing that very sick ducks I've had seem to relish is blueberries. I buy the big ripe ones, soak them in a bowl full of 1 tb. lemon juice or vinegar and filtered water for 5 minutes, then rinse well--this will remove any pesticide residues. Cut up the blueberries and put in a little ramekin with a little water.
You could also give your duck something to alleviate the effects of any bacterial or fungal toxins in its system...such as 10 mg of alpha lipoic acid per day (put it in the blueberry water). When my duck had asper, it was blowing air like a bellows, so I also gave it something to strengthen its heart, which was coenzyme Q10...the supplement store sells it in softgel capsules of 30 mg each. Your duck could have half a capsule with its blueberries (15 mg/day).