Third eyelid in Balinese kitten

I got a new Balinese kitten 3 weeks ago and it had diarrhea.  Now my other Balinese cat aged 11 months has diarrhea and has developed a third eye in both eyes. The vet first said it was an eye infection now they think it has caught something called rotavirus from the kitten.  I have been taking her to the vets for antibiotic injections as she won't take tablets.  Her eyse don't  look any better.  She has just had her second dose and is due another lot in two days.  I'm concerned it's something else.  She is still a little lethargic and is not herself.   She is eating and drinking.  I will keep you updated on her condition.  I'm new to this web site and this is my first post. Good luck everyone.

Hi Caroline and welcome to The Cat Site!
I've moved your post to a new thread of your own.
I hope you can get some answers and your cats improve soon. How is the younger kitten doing? As I understand it, your new kitten had a virus which your older kitten caught. Are they both still sick from it?