Heavily inspired by the far superior story of  Ascension, Abdication, or Abduction?
(go read that one instead as well; you would enjoy it)

He is a regular man down on his luck, struggling to find a job anywhere and escape the judgmental glare of his family, who, with each failure, start seeing him as nothing but a leech.

Just as a glimmer of hope for a job interview appears, his life takes a drastic turn. He finds himself in a parallel world, a realm teeming with unfamiliar species, and to his horror, he has transformed into a mutated version of one of them.

To make matters worse, his luck seems to have made the trip as well, manifesting in a more literal way, now homeless, cursed, and without anyone to turn, the human will have to find a way to climb out of the hole he ends up and find a way home, and avoid letting despair consume him.