A penalty from Paul Wotton and a well-taken effort from striker Reuben Reid secured the Pilgrims all three points and left Sturrock's side six points off the play-off picture having won just one of their last half a dozen games.
That sole success may have come away at high-flying Port Vale, but during that sorry sequence the Shrimpers have now lost to Barnet, AFC Wimbledon and Plymouth and have been held at home by Torquay, all of whom are batting for Football League survival.
"Just like everyone else here I'm exasperated by that performance," Sturrock said.
"I let the players talk things through among themselves and hope they can get to the bottom of what they think is going wrong.
"They've heard my voice often enough this season but I still want a few home truths to be told in there.
"I don't want to be making excuses but our injury situation isn't helping and we need to get back to having a settled side if we are to avoid our season fizzling out.
"I also think it's important we try and get some confidence back before the JPT final."