They have Mycoplasma gallisepticum (MG) and probably infectious Coryza additionally they run together. It is an infectious bacteria caused by unhygenic conditions. Hopefully someone can recommend the usa medicines. I live outside the United States and the antibiotic availiblity is more free where I live, but i do successfully treat this and clear it up in a few days. That does not include the weight loss.
I give Enrofloxacin, Oxitetraciclina, Tilosin, and lidocaine eyedrops. It is reliable but unfortunately in the usa unavailable. I wish i could send you the medicine! Tilosin is one of the medocines, but unfortunately it does not work very well by itself.
The good news for you is if you can clean her eyes every morning, and give her the tilosin injecctions, they will eventually get better. MG and coryza is not fatal, it will go away, so their lives are not in immediate danger.
For the weight loss - Do you ever deworm? It may be very likely that worms have weakened their immune systems and they are fighting those as well. Worms will possibly be fatal if untreated. Stop the corrid because it will suck all the thiamine and possibly cause even further potentially fatal problems without treating for worms.
I pulled this guy in the photo and dewormed him first, then gave the antibiotics, and he recovered in a day and a half. The sticky eye discharge is MG, and you will have to help her clean her eye in the morning with a warm cotton washcloth and water. She should eat when her eyes are clean, and then sit quiet all day in a corner.
Please ask any questions. Sorry I cant help with the medicines but tylosin is definitely part of the treatment and it will clear up with that on its own.
The fluffy feathers could be mild vitamin deficiency setting in, again caused by worms and corrid will drain even more the vitamins. Worms or not, i always deworm a bird that is sick and they almost always have worm problems!
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