My Brandy had the swollen eye tissue when she was a kitten a few times. It looks like she got pred-sq(predisone?) shots, neo poly dex eye ointment, baytril, clavamox, and amoxidrops, on various occations. I don't remember what worked best as of now, but if it comes to mind I'll post.
She's recovered fine nowadays, as she was younger then 1yr when it stopped, now she's 5. I suspected the insulation in unfnished basement she was getting into, but still don't know for sure. I'm glad you posted because maybe it was just a virus after all. Her paranoid behavior made her hid in the unfinished basement whenever a visitor showed.