Visit your network switch. Do the cables come out of the wall, and go directly into crimped-on clear plastic RJ45 (8P8C) plugs, which then plug directly into your switch? Crimped-on plugs are usually my first suspect when there is a connectivity problem.
You could certainly swap the switch-port for your room with one of the other rooms, and see if that makes any difference. However, if your crimp is bad, it could potentially start working again when the cable is flexed, leading you to believe that the switch is somehow the culprit.