I dont know if it is the breed or what, but I have three coons and it seems to be an almost constant passing around of eye infections. It does not affect the other two kitties though.
For my guys, usually gentamycin drops work...if the stain is negative for damage, the next step if it is really stubborn is cortisone drops. I have had episodes with one guy that required 4-5 rounds of treatments before it cleared...
I second that she should be seen by a specialist...better to be safe than sorry