I'm not feeling well

I was thinking about what to title this post, since I like titles that consist of only a portion of an easily recognized idiom. But most of our idioms for being sick don't make any sense:

Under the weather
It's about 78 degrees outside and sunny, with a light breeze. It's a beautiful day, no question about it, and it's been nice most of the last few days, although maybe a little on the warm side on Saturday. If I was under the weather, literally, I assume that would mean I'd be outside. I'd be outside because the weather was nice. Being outside on a nice day has nothing to do with being sick. And when I get over this head cold I won't go around saying I'm "over the weather," which makes no sense at all. Not that being under the weather does, either. And anyway, I'm inside right now, so if anything I'm avoiding the weather.

Sick as a dog
Jackson is not the sick one here, I am. I have a head cold. Jackson is probably bored right now because I'm not playing with him, but he isn't sick, ill, unwell, or otherwise suffering from physical malady. That said, he does go to the vet a lot, but when I think about Jackson, I don't think of him as being sickly. And other dogs in this building are generally in good health, too, although there a few that are unwell and in their declining years, and one even died recently (I'm sorry, passed away). But if I was looking to describe myself as sick, I wouldn't point to the dying dogs in this building; after all, there are dying people here. I could say I was as sick as one of them, but that would be considered rude, and, anyway, I'm not dying. I have a head cold. I am not as sick as any dogs I know of right now, and in any event I've never known a dog to get a head cold. I'm as sick as a Smitty.

At some point I expect to get better, and then I will be back on my feet
What, I'm not on my feet now? Well, actually, no, right now I'm sitting Indian-style on the ground in front of the chair, because I have to use the chairback to prop up the lid of this POS laptop. I can't do this for as long as I could when I was ten years old. I think I could sit Indian-style for days at a time and not be any the worse for wear when I was that age, but nowadays my butt gets numb after about ten minutes and I have get up and walk around. And at that point I'm on my feet, even though I'm still sick. It would be one thing if I was bedridden with illness, but I'm not, and yet people still refer to someone as back on his or her feet after even a minor illness or a financial setback--and I really don't get the financial use of this phrase.

In any event, it's a very annoying sickness. At first we thought it might just be a bad allergic reaction to pollen, but it's not like there was suddenly so much more pollen in the air on Sunday than there had been on Saturday. Anyway. It's a bit of a bother, though, because I have a lot of things I need to do, and I just don't feel up to it (another idiom) right now, mentally more than physically. My head is somewhat foggy, though it's better today than it was yesterday (I didn't sleep Sunday night what with the post-nasal drip). I hope by tomorrow to be more or less over this, at least enough that I can get back to work.