HELP!!!! MY CHICKENS ARE SICK!!!
Can you post a video of the strange squeaky noise?
Personally I would finish the Corid before giving anything else. After the Corid dosage (5-7 day) you can give some probiotics and poultry vitamins for a couple of days.
IMO If you are not seeing any signs of nasal/eye discharge, coughing, wheezing, sneezing or any other issues of respiratory illness then I would not treat with antibiotics.
Chickens will normally wipe their beaks on the ground, bedding, coop, wood, your pants legs, shoes, etc., to clean off their beaks after eating, drinking or when they have been digging a hole.