Substitute Connor Wickham volleyed home at the far post in the 69th minute to condemn the Foxes to their fourth defeat in seven games. They have taken just five points from those matches, although they remain fifth in the table.
Pearson said: "I think the biggest thing today was that we looked a side having a bit of a crisis of confidence at the minute.
"I can't fault the players for their efforts, but we were not fluid and didn't solve the problems Wednesday gave us. They came with a solid foundation and things didn't quite go our way for a number of reasons. We are a bit inconsistent and unfortunately for us at the moment it is not just quite happening.
"But I have a strong belief in these players and the collective spirit is going to serve you better than the individual approach. We looked nervy at times and at this stage of the season you don't really want that. We have got to keep our nerve."
Wednesday manager Dave Jones was delighted to see his side bounce back from the disappointment of defeat against Watford on Tuesday night.
Jones said: "The performance was a follow-on to the other night. I talked to the players about belief and I felt let down by the officials on Tuesday night. But I said to the players we have to forget that because this was another big game for us.
"It shows you how far we have come as a football club because when we played them in November they were far the better team and we had some catching up to do.
"Every manager will tell you they have a game plan and we had one. It didn't work the other night against Watford, although it should have done in all honesty. But today we didn't switch off at all.
"The centre-halves were magnificent, throwing their bodies on the line, but they all were. This is not the easiest place to come, although I have had joy here in the past. Hopefully the run will continue because the players had to put a shift in today against a very good side."