"Have you been happy recently?"

On today Ohno AD (I read it, here), he asked this question.
"Have you been happy recently?"
Well, in my case, to answer his question, to be honest, I am not sure myself.
When I read this line, I was like ... loss.

What with this feeling?
Do you know the feeling where all of sudden you feel down without any particular reason?
You are simply drown into your own loneliness?
Isn't that weird?
How human emotions work.