All my chickens losing weight. Got worm results back. Need help

I have 26 birds (3 Guinneas, 2 ducks, 1 turkey, 2 roosters, and 20 assorted hens). Their coop at night is a 20'x20' barn room w/perches. They free range during the day. They have been losing weight (except the turkey and ducks) significantly over the last 1-2 months. Breastbone is prominent. They still eat all the time, drink plenty, and look like they are enjoying life on the free range, but they are losing lots of weight and their feathers seem to be "frumpy." They also have bad diarrhea.

In the last 10 days two of my older hens have dropped dead. They had no weight on them. I have: dusted them for mites (2 weeks ago), sanitized and cleaned the coop (2 weeks ago), wormed them for round worms (1 week ago), and started them yesterday on CORID for cocci.

I finally got some worm results back today. Here were the results.

It doesn't look to be very high egg count, right??? They have the presence of roundworms, whipworms, tapeworms. They tested negative for Cocci.

So, any thoughts on what is going on with my birds? Any suggestions for treatments. I just finished the second day of treatment of CORID. Should I keep that up for another three days?

Please help before I lose my entire flock. Much appreciated!

 

It is the same feed they have been on for two years - Dumor Laying crumbles. We also have been mixing in DE into their feed too over the last two weeks to address the potential worm problem.

 

Good question. I wasn't sure if it was like human antibiotics, where once you start something you need to finish it so they don't build a resistance. I also didn't know if CORID had any other helpful use in treating worms.