Unfortunately, I've had several chickens suffer consequences of neuro toxin poisoning. All petroleum distillates produce these toxins and the effect on chickens is the same: first balance problems, then progressive lameness, followed by shutdown of motor functions.
Is your chick displaying any of the following symptoms? Difficulty holding its balance, trying to compensate by propping itself on a wing, ceasing to be able to stand and walk. Eventually, it will not be able to eat drink or swallow.
If none of these symptoms are present, you are not dealing with insecticide poisoning. You could be seeing impacted crop, not to be ruled out, chicks being gluttons. If you feel a rock-hard knot in the crop, administer some oil, massage the crop until the mass softens, then give plenty of clean water.