The 3-1 defeat at the King Power Stadium on Tuesday night was Blues fifth game without a win and has seen them drop out of the Championship play-off places and down to eigth in the table.
"We've got a group of players who for such a big part of the season have been so good," the Blues boss said after the match.
"We're going through a difficult period at the moment, which every team will do at some stage in the season.
"This will have been the most difficult period among all the games we've had, we need to come out of it and the only way you do that is by sticking together, maybe getting a scrappy 1-0 win.
"But you still have to have belief in what you're doing. It certainly can't be a time to panic because there's a short period of time now."