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In my opinion antibiotics can be used for supportive care to treat any secondary infections from EYP, you will have to decide "how long" is long enough when continuing treatment. Quality of life can sometimes help in making that determination.
Here is some info on EYP. There are plenty of articles here on BYC as well.
The stance does look like EYP. The meds should give her supportive care and help with any secondary infection.
It sounds like you are doing all you can do.
I don't think the swelling will ever really go away. Unfortunately from what limited knowledge I have on the subject there is really no cure. so supportive treatment and care is the best you can do to prolong her for a while. Just keep an eye on her, give her the TLC you have been giving and make her as comfortable as you can. I think you will know when she starts to decline.