Good trope that never ever gets old

Character has a really bad coughing fit and when they finally catch their breath they pull their hand away and there's blood on it and I'm not doing this explanation justice but ugh just the way their eyes widen with the realization that oh shit this is really bad. Even better if they decide then that their friend/partner whathaveyou must never know about this which ofc leads to angst because the sick/hurt one physically feels like shit as their condition get worse and worse, and then there's the emotional angst that happens when they eventually hit their limit and can't hide it anymore and the other character(s) find out