I think a big part of it is being absolutely flustered by constant human presence. At the store I'm surrounded by people, and at home I'm constantly surrounded by my brother and his girlfriend. They're just always there.
You can kinda see it as a wound becoming numb due to intensity, rather then gradually damaging and healing and so growing a thicker skin.
It's a situation where you know you're doing good, but drained in being/doing so. Which in my case results in strong desires of absolute calmth, isolation and serenity a certain amount of hours in the day, not getting that is stressing.
It's nice to know you're good, though. Those momentary streak of good days are a warm welcome I reckon. Even if they don't last forever, it's nice to know you can still have them occasionally, right? :3