The Magpies manager watched in dismay as, after making a positive start against the League One leaders, his team crumbled to a 5-1 defeat at Brisbane Road.
Danny Haynes notched Notts' only reply on a dismal night for the league's bottom side.
Kiwomya said: "There was nothing in the game in the first 25 minutes when we were as good as Orient, but we gave away a needless free-kick and they scored.
"We then conceded another at a bad time allowing people to run off us too easily and then concede another through a lapse of concentration.
"Once we go a goal down, we look very fragile and we are always climbing mountains. We got back to 3-1 but we were still scampering forward like mad because there was still a lot of time left in the game to try and get level.
"But we were leaving holes all over the place and I'm disappointed because we've got some experienced players out there who should be leaders. There is only so much I can do from the touchline.
"Those players have got to take responsibility, we can do all the planning and talk tactics but once they cross the line, it's down to them."
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