Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
quĕrēlor, āri, v. dep. n. [querela], to make a complaint, complain: de malis praesentibus querelatur, Arn. in Psa. 76: eum querelantem invenimus, Serv. Argum. ad Bucol. Verg.