Sorry Toki that you've been feeling like that. It is very similar to how I feel at times, and I really, really hate it. I can be around my my husband and he'll be cheerfully talking about upcoming plans or such, and when in that mood I'll just be so irritable I don't want to hear him or anyone. Then I feel really guilty. I am pretty good at not snapping at him or others (from very long practice), but I think most people can still tell that I'm not in the best of moods.

It's usually triggered in me by sleep deprivation, an overload of stressful situations/people acting up concurrently, ruminating on negative/traumatic incidents from the past a lot (which also causes stress), or, just a bout/mood of plain old depression that comes wrapped in irritability, the trigger of which isn't clear to me, though it may or may not be later.

Hope your down mood lifts soon.