Chicken is making weird noise, sneezing with diareah, HELP

[Kitkat4123]

Its been extremely warm lately, so I don't know if that's got anything to do with her behavior, but I've never had this before?
In between breaths she makes a weird noise in wich she full opens her mouth? She also sneezes very regulary, some in wich she shakes, and then gasps for breath, only to continue making the weird noise. I put her apart, and noticed she has diarreah, wich is fully dark and watery. (photo below) She's 4 years old. I noticed something was off when she refused to eat.

 

[DLA]

She may have some kind of respiratory infection but I'm far from knowledgeable on this subject. Perhaps someone with better experience can answer please.

 

[DLA]

https://www.backyardchickens.com/articles/causes-treatment-and-prevention-of-chicken-sneezing.77453/