A late winner from West Essex's skipper Tom Macleod gave the hosts the three points.
Jerome Martelli had put 'Side ahead five minutes before the break. It was the forward's first goal for the club since the opening day of the season when 'Side won away at Great Wakering.
West Essex though hit back frustratingly two minutes later to level. Cameron Gray firing home after good work by Michael Mignot.
Just as it looked as if the spoils would be shared, Macleod headed home a Joe Lefley free-kick deep into injury-time to consign Michael Walther's men to defeat and a place in the bottom four.
'Side: Joe Simmons, Akil Clarke, Ricardo Bailey, David Etcheri (Gareth Jones), Joseph Huston-Mendy, Paul Shave, Hayelemariam Seyoum, James Briggs, Roddy Lemba, Jerome Martelli (Jayden Mitchell-Brown), Mattheus Santos