My nearly 5 week old Welsh Harlequin duckling, Sage, has a pretty nasty sounding cough today. I was in there feeding/petting them and she coughed numerous times and it sounds congested. She must be coughing something up that I can't see(no obvious mucous at mouth or nose) because she kind of moves her bill around after she coughs like she's feeling something. She has always lived with 3 other ducklings in my duck brooder, they all came from the same feed store, and she still lives inside my house full-time. She has never been exposed to anything unusual besides my chickens and my geese on occasion. I fed the ducklings a couple crickets(store-bought) and mealworms a few days ago for the first time. Other than the coughing, she acts pretty normal. She is inquisitive about what I'm doing in there, wants to be petted, saw her eating and drinking this morning. Does it sound like she has gotten sick? I hope she didn't aspirate something while she was eating and I wasn't around. If she is sick, what do you think the illness would be? What medicine should I treat her with, and what dose? I have a pack of Terramycin that I have never used.