Scheduling disagreements

Hiya all. I work as student nurse at a local hospital. I have my LPN and work as that, but i'm under education and have the other title of "student nurse", so I float floors. Since I don't have a specific unit, I go through the staffing office for my scheduling. This weekend I had said I was "available" but there were no shifts open when they sent out the schedules. I was in the staffing office yesterday and the lady didn't say anything about having to work this weekend, so I didn't think anything of it.

I get a call at 7am this morning asking why i'm not at work, the conversation goes like this:

House sup: Why aren't you at work?

Me:because i'm not scheduled to be there.

HS:yes you are. 5west 7a-7p, it's in yellow on your schedule I have in front of me

Me:thats funny, because mine is pink saying i'm "available" but there were no open shifts and no one said anything to me about working

HS:so when are you coming in?

Me:i'm not...i have the flu, coughing, sore throat, body aches...i'm not coming in

HS:you realize you're on the schedule for today and tomorrow?

Me:No, I was available to for today and tomorrow but i'm sick and no one called to ask if I still wanted to work it. I'm not available.

HS:ok, well i'll see if I can find someone else to work.

Me:okey dokey

*click*

Note:a yellow on our schedule means "change" soooo it went from my pink to her yellow, but no one told me of the change?? I have a cough, a slight temperature, and sore throat, should I have sucked it up and gone in? Or were they just trying to take advantage of the fact that I don't have a floor supervisor to alert me to these changes??

I don't know. I love my job at the hospital, but now i'm looking into long term care while I finish my RN degree (it'll be May when I graduate).

Any ideas?