Little tiny black flies in bathroom:(

[Haily111]

Hello i keep on finding tiny little black flies in my bathroom. Have read previous thread and i dont have any pot plants. Also they are only in my bathroom. Can they actually come up from the sink??? I closed the door and window, stuck bleach down every bloody hole and they are still popping up from somewhere. Am starting to get frustrated :-(

Can't remember what they are. We occasionally get them. I pour boiling water down the sink, later followed by bleach. Usually does the trick.