Increased respiratory rate no discharge

[Glendaroost]

Hello, I have two older silkie ladies (approx 8yo, had them since 16 weeks/POL) which are both looking a little hunched and with higher respiratory rates than normal, about 60 per min. One is also tail bobbing a little bit but only occasionally. No discharges, sneezing or any noise aside from slight clicks on respiration when listening with a stethoscope. We have had excessive rain lately so I wondered whether aspergillus could be the cause. They are being nebulised with f10 and have ordered some vet rx. Just looking for any thoughts on what might be going on

 

[Myrshine]

Could they be stressed? Too hot? Perhaps have weakened hearts because of their ages?