complicate vs rub salt in the wound

complicate

verb
  • To involve in a convoluted matter. 

  • To make complex; to modify so as to make something intricate or difficult. 

rub salt in the wound

verb
  • To make an injury, physical or emotional, feel worse. 

How often have the words complicate and rub salt in the wound occurred in a corpus of books? (source: Google Ngram Viewer )