My baby blue Swedish was taking a bath in the bathtub, and I took it put and bubbles were coming out of it's nostrils and it's little eyes are closing and opening slowely. Could soap made him like this??
Sounds like another bath with just plain water is needed. I would want to be sure that all and any soap is off the duck.
Remember to use water that is warm but not too warm for the duckling. How old is he or she? The rule of thumb for brooder temperature is 90F the first week, dropping about 5 degrees F each week. I used that to decide how warm the water ought to be.
And some of my ducklings needed to be dried off with a clean washcloth after their bath-swim time.