Please help. My Pekin duck has been coughing,shaking his head and sometimes wheezing. He has been like this for about 3 days now. He's is eating and drinking normally and acting normal other than the coughing. I have mixed some rooster booster and vet rx in his water. By what I'm reading online I think it could be gape worm and know it could be fatal if not treated. Any help will be greatly appreciated.