Please help me try to dx my flock - or at least what to try next!

1) What type of bird , age and weight (does the chicken seem or feel lighter or thinner than the others.)
It is the entire flock, ranging from birds about 7 years old to 2 years old - various breeds

2) What is the behavior, exactly.
Not laying, sneezing, wheezing - but NO discharge

3) How long has the bird been exhibiting symptoms?
haven't laid in about 4 months

4) Are other birds exhibiting the same symptoms?
all of em!

5) Is there any bleeding, injury, broken bones or other sign of trauma.
nope

6) What happened, if anything that you know of, that may have caused the situation.
n/a

7) What has the bird been eating and drinking, if at all.
normal eating and drinking

8) How does the poop look? Normal? Bloody? Runny? etc.
normal

9) What has been the treatment you have administered so far?
dosed with wazine
then 10 days of Tetracycline...800mg dosage
14 days after wazine, does with ivermectin
It has been about 2 weeks since wazine

10 ) What is your intent as far as treatment? For example, do you want to treat completely yourself, or do you need help in stabilizing the bird til you can get to a vet?
cure the buggers

11) If you have a picture of the wound or condition, please post it. It may help.
n/a

12) Describe the housing/bedding in use
they sleep in a coop, wood shaving litter. We very recently have started the deep litter method - as in last week. Free range during the day generally

They exhibited a lot of gape worm symptoms, but the wormer did not help at all. The Tetracycline helped a little, but it must have been some sort of secondary infection that it cleared up, because they were not as sick, but you can easily hear them wheeze if you are near them. I don't think it it coryza, they have no discharge and no mortality.
I am guessing I should try some kind of injectable abx next, but not sure what to try.
No knowledgable chicken vets in the area