(only seramas) sneezing, and rattly but no discharge?

[arockkid]

Looking for help, advice with my 4 seramas who began sneezing a few weeks ago. I didn't think much of it, because they are all acting normal, otherwise.
The sneezing is quite frequent, and only today did I bother to snag one up and you can definitely feel a rattle in her lungs, but there is absolutely no discharge.
Doing a bit of quick reading, they also pass the smell test (as far as chickens go) and everything seems relatively normal, although maybe there is some slight reddening around the eyes? I have a lot of other birds in a mixed flock, and these are the ONLY ones sneezing this way.
Important to note, I just switched to pine pellet bedding in my stalls, and also have been running a fan which seems to coincide with the sneezing, and my other birds all sleep in the coop, except these 4 who choose to perch on the stall door.
I'm nervous to have some disease run rampant, though as I said, it has been weeks and there is no discharge.
How would you move forward if it were you? Do you think it could just be from hanging out directly in front of the fan much of the time?
By the way, these are adult birds.

 

[Eggcessive]

You could be dealing with a virus caused IB or infectious bronchitis or a mild case of mycoplasma (MG.) You can start some antibiotics such as oxytetracycline, Gallimycin, or Tylan Soluble Powder to treat them or prevent secondary infections. IB will make carriers of the birds for a year, and MG for life. Always make sure that you have plenty of good ventilation, no ammonia fumes, or wet or moldy conditions that can cause breathing problems. Here is a good link to read about these and other diseases: http://edis.ifas.ufl.edu/ps044