Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
perplexim, adv. [perplexus], intricately, confusedly, perplexedly: utrum ego perplexim lacessam oratione ad hunc modum, an, etc., Plaut. Stich. 1, 2, 19 (76 Ritschl); Cass. Hem. ap. Non. 515, 20.