Hi everone, I'm new to Backyard Chickens, but I need your help. I've had chickens for many years, but never come across gapeworm before. I bought 5 young dominique hens last fall, who were free ranged. In no time, they were shaking their heads like crazy, with occasional gaping. After researching on line, I thought they prob. had gape worms, so treated first with wazine, then with 1/4 cc of ivermectin orally for each hen, followed by the same dose 14 days later. Now the symptoms have come back. Any suggestions? Does food grade diatomaceous earth work? If so, how do I use it? Thank you!