Injury with no sub available.

[Nevadaref]

Billy, since you asked: This was the governing NFHS ruling prior to MTD convincing Mary Struckhoff otherwise and getting his case play put in the book.
Most on the forum are aware that Mary was certainly no rules genius, as evidenced by her infamous backcourt interpretation.

2002-03 NFHS Basketball Rules Interpretations
SITUATION 5: Team A is playing with five players, but has no remaining substitutes available when one of the players has an asthma attack. The coach is beckoned onto the floor. RULING: The player must leave the game unless a time-out is requested and granted to Team A with the player being ready to resume by the end of the time-out. The team may continue with fewer than five players if there are no substitutes available. An injured/ill player may return to the game after recovery. (3-3-5)