It appears you have a respiratory infection in your flock. This bird is sneezing and wheezing badly and the other bird's swollen eye will have been caused by it too. I don't know enough about antibiotics to advise on what would be appropriate. Here in the UK it would mean a trip to the vets because we can't buy anti bs over the counter like you can in the states. If you do some searching via the "Search Forums" facility at the top of the page under the "Home Forums Articles Reviews" etc headings, you should find info on which antibiotic to use and what dosage. It may be that you have to buy injectable because the rules in the USA changed in Jan of this year regarding animal antibiotics to be added to food of water needing to be prescribed by a vet, so if you are not confident injecting a chicken you may need a vet anyway.
It may be that your vet will prescribe an antibiotic to put in the water without seeing this chicken, if they have recently seen the other chicken and you explain the circumstances. You could even perhaps email the video so that they can see the problem without stressing the chicken by taking it into the surgery and potentially infecting other birds....always worth stressing that it may be in the vets interests to prescribe without taking the bird in. Respiratory diseases in chickens are usually very infectious.
Vet RX is a product specifically formulated to ease respiratory symptoms in chickens and can be purchased over the counter but I think that legbar in the video may well need stronger medication in the form of antibiotics, although Vet RX may give her some relief until you can get something stronger. If you lay your hands on Vet RX today, I have used a little drop of eucalyptus oil rubbed on the beak to help open the airways.
Hopefully @casportpony or someone equally knowledgeable will be along soon to give you antibiotic info.
Good luck with her
s this the same bird you posted about on Monday?
This is a different bird - we took the eye-chuck to the vets and got some drops. Happy to say the swelling is down now. I do wonder if it's somehow related though