heavy breathing RIR, Very concerned

[foxmfan1]

HEllo, IM kinda new here, my ladies are about four months old, I only have three two RIRs and one leghorn, so far they have been excellent. today though, one of my RIR is breathing heavy, and sounds like she has a "sore throat". She is eating, and pecking and drinking water, normal, she will be ok then kinda stretch up her neck and take a deep breath I noticed she is open mouth breathing and when she squacks it sounds like she has a sore throat, i am worried. I am going to get up and get some antibiotics from the feed store in the morning, BUT is there anything I should be looking Its been raining and they were out foraging in sprinkles not in heavy pour, they go in the patio , but its been wet lately the past few days. any help i appreciated. Worried mama hen, right now : (