Swollen and pale comb otherwise active. Help please

[Three Little Chicks]

Hello BYC folks. I'm new and am looking for advice on my 1 year 3 month old Rhodie named Agnes. She went through a few cycles with shelless eggs, and popped back well but then started getting pale in her comb and is now swollen in her comb base and left side of her face. She is otherwise active, eating and drinking. She has plenty of calcium, and I've been trying Apple cider vinegar dilute and thyme leaves to boost the immune system. No evidence of mites ticks or worms though I am deworming now with Corid in water. They free range regularly but nothing has changed, though we have crazy pollen now could this be an allergy,? Doesn't seem to be a sinus infection and no wheezing or coughing or scratching. Attached are images some include a healthy hen for comparison.
Many thanks. Cheep cheep cheep

 

[WIchickMama]

is it really hot where you are, could she have heat exhaustion at all?

 

[Three Little Chicks]

is it really hot where you are, could she have heat exhaustion at all?

I'm in coastal Massachusetts no not hot enough we've been in the 70'80's and they have ventilation on 3 sides of tractor coop with a good run. The others are all fine. But thank you for the suggestion!

 

[Three Little Chicks]

So update, I've scoured the countryside for Bayrtrtril or penicillin but
the folks at TSC really tried to help they just didn't have the products. I did get some Duramycin an antibiotic for cattle and swine, based on the dosage conversion a chicken would get about .10ml for 2 pounds. 10 drops is 1ml.....so 2 drops is .1ml for 2pounds of animal. Has anyone used Duramycin?
I've ordered baytril form www.allbirdproducts.com
Should I wait to get the Baytril or has anybody successfully used Duramycin? This is definitely the injectable so I'm not anxious to stick her if others have had bad experiences with it

 

[Three Little Chicks]

Just a note, for those who pitched in with thoughts on my Agnes, as it turns out she did have cancer. it took a year or so to eventually kill her and when it was time I put her down with an injection peacefully went to sleeeeeeep... then I bawled like a baby. She had masses inside which I could feel with a rectal exam, and they didn't move as bowels emptied. maybe this might help someone else. Kudos to Oceanside Animal Hospital in Sandwich MA for their most excellent care and consideration for chickens in general. Diagnostics proved my suspicions, and we saved her the most painful of days. Thank you WIchickMama for responding, she did have another good year before heading out under the apple tree.