wheezing chicken-please help!

[Jillybean2411]

I had 8 chickens ranging in age from 1-3years. I've lost 3 hens since February. my 9 month old silkie died suddenly in February, didn't notice any symptoms I hadn't been out to the coup in a few days as I was ill and my husband was caring for the hens. He just found her dead no signs of injury (he's not the most observant person in the world so he may have missed the symptoms). A month later My 3 year old hen Babs was fine in the morning when I let them out into the yard and that night when I went to shut them in she was laying on the ground outside the pen gasping for air. I brought her in the house to warm her she kept laying her head down and closing her eyes and gasping. By the next morning she had died. Over this time my 3 year old hen Nora was looking egg-bound with her tail down walking like a penguin and opening her mouth to breath and coughing, her comb turned pale but otherwise she was fine, eating & drinking with a normal energy level. I spoke to the self-proclaimed "chicken-expert" at the local feed store who told me there was nothing I could do. Nora went on like this for 2 months before I found her laying in the pen gasping for breath, she died shortly after.

Now I am noticing one of my other hens making a squeaking noise as she breathes, it's not all the time and she is otherwise healthy (she sometimes has loose droppings). I have spent hours researching, could it be gape worm? I read that gape worm is really rare. I bought Wazine17 at TSC and a bag of duramycin-10 not sure which I should try first the dewormer or the tetracycline?

Will wazine kill gapeworm? I've never de-wormed them. Their poo looks normal, could worms make them this sick?

I can't bare to lose another one of my girls
Thank you!
Jillian