Oh my, I am so sorry you have lost so many. I use an herbal dewormer so sorry I can't help on dose but here is a link that may help:
I need some help PLEASE!!!!
I want to deworm my flock, I have over 50 birds, so doing each one individually is not something I can do. I bought ivermectin pour on and I also bought safe guard for dogs( this is a packet of stuff that you can dissolve in water). My question is which one is better and at what dose do I give. the dog stuff says it has 4g per packet or 4000mg. I was thinking of dissolving one packet in the water. I have almost 30 birds in the one area, would this be enough or not enough. I just don't want to kill them, I already lost over 20 chickens last week to a horrible 2 day attack from coons, I cant handle loosing anymore. I just need to know dosages please.