If you are only sick for 24 hrs, then most likely it's NOT the flu. There are a lot of other viruses that will give similar symptoms. However even w/ a mild case of a true flu virus (seasonal or H1N1) you will be sick for longer than 24 hrs.
Trust me.....I'm battling the whole "we don't test thing" in my head right now.
In September I started coming down w/ something on a Wed-- was sick and in bed Thurs-Sat-- felt run down but better on Sunday- back to work Monday. Nobody in my house caught that from me. They gave me Tamiflu then. I had no fever, but did feel really run down, bad cough, bad nasal congestion. They told me then it was "presumed flu". However, we were not seeing any cases in our area (at least at the large clinic I work at)
Fast forward to this past Friday, I was at work in the morning and felt fine-- after lunch I was getting the chills within 2-3 hrs I could barely drive myself home. My head was throbbing so bad, I had a fever, my throat hurt, I was coughing, my entire body hurt more than I can ever remember. This time I had the "fever" and it hit me out of nowhere. I started Tamiflu again this past Saturday. The difference is that this time I was exposed at least several dozen times the entire week to people who did in fact test positive for influenza A (presumed swine flu). I did end up in the ER on Sunday because it felt like my asthma was flared up (it wasn't-- I thinking I was having anxiety). They wouldn't test because I already had 4 doses of Tamiflu by then

. I then seen my doctor last night and asked if he could do a rapid flu and he said the same thing--- too many days have passed and I've been treating it. The result might not be accurate. Anyhow, this time they feel more confident it's the flu and put me out of work until next Monday. Oh and this one my husband has now too.
I guess what I'm getting at is......I know why they aren't testing at the lab. However, I do think they should do more rapid in office tests. There is a part of me that would at least like to know if I can relax a little bit about this virus. I've been on pins and needles stressing about getting it. I think and pray I'm on the downside of it now.....I'm still congested but been fever free since Sunday during the day.