Having shuffled his starting XI once again following the 3-0 defeat by Huddersfield on Saturday, Stuart Pearce saw his side concede twice in the opening 35 minutes and lose defender Jack Hunt.
Britt Assombalonga, relegated to the substitute's bench, was thrown into the fray at half-time but the game was over as a contest just minutes later when Pritchard netted a penalty for the visitors.
Down to ten men for the final ten minutes after Danny Fox left the field injured with all subs used, Forest gained some credit with the City Ground crowd, who remained supportive of their team throughout, when Michail Antonio reduced the arrears.
The Reds, however, are now without a win in ten games and down to 11th place in the Championship table with Pearce saying afterwards: "I’m not going to be morose, I’ve got a job to do at this football club, a club that I love very much, and I’ll carry on doing that job. It’s down to me."