c. 1200, creulen, "to move slowly by drawing the body across the ground," from a Scandinavian source, perhaps Old Norse krafla "to claw (one's way)," or Danish kravle, from the same root as crab (n.1). If there was an Old English *craflian, it has not been recorded.
Meaning "advance slowly" is from mid-15c. Sense of "have a sensation as of something crawling on the flesh" is from c. 1300. Related: Crawled; crawler; crawling.