Caretaker boss Graeme Murty suffered a second consecutive defeat when Billy McKay netted an 89th-minute winner for Inverness Caledonian Thistle on Friday night.
The 2-1 defeat saw Rangers drop more points in the race for second place and left them without a Ladbrokes Premiership victory in four games.
Rangers failed to build on Martyn Waghorn’s penalty equaliser midway through the second half, losing the initiative, and Wallace was at a loss to explain their indifferent form.
The left-back told Rangers TV: “It is happening too often, it has happened too often this season and it’s really hard to get your emotions together now and assess how we have been in recent games and how you look at the whole season.
“There is no way I will stand here and make excuses for anything, we have to get our chests out, get our chins up and we have a massive responsibility on Wednesday to put that right.
“I don’t know the answer to why the performances aren’t happening, it has been disappointing and losing two games in a row is not a feeling you should have at this football club.
“It is a really shocking period just now and as you can imagine it is hard for me to put the feelings into words, it is not a nice place right now but we need to get ourselves together and take it from Wednesday.”
Rangers host St Johnstone in midweek looking for a second victory in eight league matches in a poor run which started in the final weeks of Mark Warburton’s reign.
Murty - who revealed after the game he had been receiving help from an unnamed source - looks set to be in charge again as the Rangers board search for a director of football and new manager.
Wallace said: “Now we have a massive responsibility because we thought we were coming here (Inverness) to answer the critics, to answer the questions that were being thrown at us but we have failed to do that.
“Losing the game in general is really hard to take because that is two games in a row that we have lost and it is nowhere near acceptable for this football club.”