When my cats had stuffy noses I also found that giving them a steam bath helped SO MUCH! I know its minor compared to what you are going through but every little bit helps.
Oh no no no plants for us. My cats will eat anything and everything (to my ultimate distress in wrapping xmas pressents, elliott ate ribbon that year and had shiny metallic poop). He is such a little scavenger that he got into my no kitty room, ate a plant he was NOT supposed to and proceeded...
