Help! Struggling to get rid of respiratory issue in 2 of my young pullets

[Brachel30]

I think this all started with a surprise rain but its been about 2 weeks and just when I think they are perking up and doing better we have another rough start to the day.
Currently giving them nutridrench twice a day, vet RX under the wing and rubbed on the beak, and duvet vitamins and electrolytes in their water with a couple drops of oregano.
The raspy rattle breathing and sneezing just tears at me because it's so pitiful. Do I just keep treating as is?? How long does it take to see more major improvement? Should I consider antibiotics at this point and if so where do I get them? Dosage?
Sorry for the amount of questions, this is my first back yard flock and first illness.

 

[Wyorp Rock]

Welcome To BYC

Have you added any birds recently? How old are they, how long have you had them?

Any changes in environment that you can think of = closing up ventilation due to cooler weather, strong ammonia smell in coop, etc.?

Raspy rattling and sneezing is usually an indication of respiratory illness. Do you notice any watery/bubbly eyes or mucous?
Infectious Bronchitis and Mycoplasma are both fairly common in poultry. You can try treating with Tylosin to see if that makes a difference.

Here's more info about respiratory illnesses https://edis.ifas.ufl.edu/publication/PS044