Lysine works for herpes, i'm not sure it works for calicivirus or any other virus. But calicivirus is so awful that we give lysine to our chronic calicivirus cats anyway, just in case it DOES work. We force-feed crushed tablets in AD because two of our cats do not like the taste.
I have given saline drops in the nose. I used the instructions from Anitra Frazier's "The Natural Cat." I mix up the fresh salt solution in warm water, put the kitten on his back, nose pointing up, and put in one drop at a time, slowly. No, he didn't like it, but he was a gentleman about it. Little Noses in a no-preservative, no-additives saline formula would work, too. But I feel a warm solution is nicer for the cat.
If it works, your cat will have a nose-clearing big sneeze or two, so keep a tissue handy.
The other thing I've tried is soaking a few very small sponges in warm water and pressing them very gently over the top/bridge of the nose, periodically, to loosen anything in there. Cats aren't crazy about this, either, but mainly because they can't figure out what you're doing. Don't cover the nostrils, obviously, just warm the nasal passages.
A vaporizer can make a dramatic difference in the humidity of the room, and will do a better job than a humidifier, I think. If you have soft water, read the directions about adding salt to make more steam.
If she has calicivirus, watch for limping or other signs of muscle pain. If her meow is very hoarse or she has lost her voice, her throat may be inflamed, or she may have mouth sores. There's not much you can do but administer pain meds, antibiotics in case of secondary infections, and offer softer, blander foods (my cat insisted on eating kibble when his throat was a mess, and he never eats kibble, go figure).
A gently heated or warm bed would probaby be a welcome comfort, too. This didn't occur to me during our outbreak, and I could kick myself.
Good luck! It's tough nursing cats through a URI so it's a relief when you can figure out anything that actually helps the poor thing.
