Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dē-questus, a, um, Part. [queror], having deeply deplored, bitterly complained of (in post-Aug. poetry): secum dequesta labores, Val. Fl. 5, 448: imbres, Stat. Th. 1, 404; cf. talia, id. 11, 627.