Siewert addressed his players in the dressing room after the game and was clearly still hurting in the post-match press conference.
Asked how heartbreaking the 4-3 defeat was after leading 3-1, he said: "Look at my face."
Huddersfield are now 16 points from safety with seven games to play.
Siewert wants his players to do everything possible to make the fans, staff and him proud.
He said: "After the game, I went to our supporters and tipped my cap to them, as you say in English. We have seven more games left to represent the club and the people working at this club because they are amazing."