I think summer is the coldest season in Taiwan. It's indeed boiling hot outside, BUT, once you get on a bus or train, you will understand what I mean. It's freezing cold!!! Guess what will happen if you're exposed to the extreme temperature swings everyday? Well, I feel sick...
So, today I'm going to tell you about how to say "not feeling well" in Japanese.
These are the 3 most common expressions.
(1) 具合(ぐあい)が悪(わる)い。/guai ga warui/
(2) 調子(ちょうし)が悪い。/choushi ga warui/
(3) 体調(たいちょう)が悪い。/taichou ga warui/
All these phrases can be translated as "I'm not feeling well". Let's see their nuances of meaning.
(1) 具合 and 調子 can also be used for machines but 体調 can't.
体調 is only used when we talk about health or body condition, as it has 体 (=body) in its word. 調 of 体調 is of 調子, which simply means "condition".
体調 ＝ 体（body）＋ 調子（condition）
(2) We use 調子 when we're talking about its performance.
Then what's the difference between 具合 and 調子? It's just my opinion, but I guess 調子 also means "performance" as well. I couldn't find the dictionary which says it means "performance", though.
Let's say, you are good at playing tennis. One day you're palying with your friend but you can't play as good as you usually do. Your friend would ask you:
/doushita no? kyou wa choushi ga warui ne/
What's wrong? You are not yourself today.
Since he's talking about your performance, it can't be 具合 in this case.
Or, if you play very well in your match, your tennis coach would say:
Way to go!!
You cannot say その具合(ぐあい). It sounds very strange.
(3) 具合 sees its condition.
It basically means "condition". We often use it with other verbs.
/shigoto no susumi guai wa dou/
How's your work coming along?
進む（go ahead）＋ 具合 ＝ how it goes, the degree of progress
/niku no yake guai ga choudo ii/
The meat cooked just right.
焼く（grill, bake, fire, roast）＋ 具合 ＝ how it cooked, the degree of doneness
You can also say いい具合(ぐあい)に焼けている。
具合(ぐあい)がいい / 具合(ぐあい)が悪い also mean "convenient / inconvenient".
/ima sono hanashi wo sareru to guai ga warui/
It's inconvenient for me to talk about it right now.
I think the key of the meaning of 具合 would be 合 (=to fit, to suit, to adjust, to match). 具合が悪い indicates that it doesn't fit what you want. You don't feel as well as you usually do. Or the schedule dosen't suit you.
Well, that's all for today. Thank you for reading!