Success

I think I figured out what my spider is: a yellow sac spider. According to that website

Cheiracanthium mildei was first identified as a cause of necrotic arachnidism in 1970, when it was linked with skin lesions in the Boston, Massachusetts area (where it is the most common spider found in houses)

He went into the yard. Not back into my room.

On top of that, there's some black and yellow orb spider in my trash can outside. Probably a garden spider, I would guess.