The Dragons were leading 1-0 at Eastleigh on Saturday and playing against ten men for the final 20 minutes.
However, Ryan Cresswell bundled home an equaliser in the last minute to extend Wrexham’s winless run to five games.
They face another tough trip to Ebbsfleet on Tuesday night and the gap between the Dragons and eighth-place is now just two points.
“It’s really tough to take,” Pearson told Wrexham’s YouTube channel after the Eastleigh draw. “It’s disappointing but it’s something that has been creeping in for a while now.
“If we want to get in there (the play-offs) we’ve got to find a killer instinct. We should have finished the game off - it’s happened too many times.
“We need to have more about us when playing ten men, it’s as simple as that. There’s a lot of anger and disappointment but we have to dust ourselves down and get ready for Tuesday night. We have to go to Ebbsfleet and get a win.
“We’ve got four massive games now. We need to find a win and quick. We’ve got to stick together and keep believing.”
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