Why does the tip of my nose and upper lip go white after I work out really hard? (photos)

Basically the skin on the nose has been traumatized from surgery and there is new scar tissue. Once this happens, it needs to develop new blood supply channels and many times this can change the color of the skin slightly. usually this is not noticeable, but in your case it seems to be more pronounced after exercise. It should improve with time as new connections are made but there is a chance a slight variation continues for an extended period of time. Best of luck