The Blues head into this evening's match against Wigan Athletic at St Andrew's off the back of a four-game losing streak.
Birmingham currently sit 22nd in the table, one point adrift of safety but with a game in hand on their relegation rivals.
"It hurts at the moment," Clark told the Birmingham Mail. "It hurts to the pit of your stomach.
"There is no time for self-pity. We are now looking forward to getting the four points we need to stay in the division – which we will get.
"Other people may not think we will. That's fine. That's their opinion, not mine. Why? The players, in that they have done it before this season."
Birmingham lost 3-1 to Leeds United in their last outing on Saturday.