I think it was an episode from The Outer Limits, or maybe The Twilight Zone. I think I watched it in the 90s, very likely in color.
I had a look at the episode descriptions for The Outer Limits of the 90s on Wikipedia but found no apparent match.
What I seem to remember is that some guy's well-being affected the world or universe he was living in, and he tried to tell everybody but nobody believed him until his condition deteriorated, causing the world to break down and (almost?) starting the apocalypse.
Which TV show episode or movie was that?