can of worms vs helter-skelter

can of worms

noun
  • A troublesome situation; an issue whose resolution is difficult or contentious but not necessarily complex. 

  • A complex, troublesome situation arising when a decision or action produces considerable subsequent problems. 

  • Used other than figuratively or idiomatically: see can, worm. 

helter-skelter

noun
  • Confusion or turmoil. 

  • A helical fairground slide. 

adj
  • Carelessly hurried and confused. 

adv
  • In confused, disorderly haste. 

How often have the words can of worms and helter-skelter occurred in a corpus of books? (source: Google Ngram Viewer )