Possible Clues:

• Moves stealthily
• Heebie-jeebies
• Crawls silently
• Willies
• Moves slowly and stealthily
• ''Tomorrow, and tomorrow, and tomorrow, ... in this petty pace from day to day'' (Macbeth)
• Unpleasantly strange people
• Crawls
• Moves silently and carefully
• Advances slowly