Hill is day to day, according to Pacers coach Frank Vogel.
Hill suffered the concussion in the first half of Game 4 after a collision with Knicks center Tyson Chandler, Vogel said.
D.J. Augustin replaced Hill in the Pacers' starting lineup. Guard Lance Stephenson also took on a large portion of the ballhandling duties for Indiana, which lost Game 5 85-75 and now lead the second-round Eastern Conference series 3-2.
Hill has been an integral piece for Indiana all season, particularly in this series. He poured in 26 points -- 13 in the third quarter -- in the Pacers' Game 4 win.
In the postseason, Hill is averaging 16 points, 4.4 rebounds and 4.1 assists.
He averaged 14.7 points, 4.7 assists and 3.7 rebounds during the regular season.
Per NBA protocol, Hill will have to complete a series of steps to confirm that he's healthy enough for competition before he returns to the court. Those steps include cardiovascular tests to make sure symptoms don't persist and a consultation with a league-appointed neurologist.