Double00

My birds have flown through the moult. nearly complete but today i have a young hen and a yearling cock looking very sick, wings down, feathers puffed out and not eatn, these birds have not been out for 2 months and have been a picture of health till today, i read somewhere that the moult can trigger parathyfoid? dont want to discard of these birds so some advise would be warmly welcomed, thank you.