eat away at

verb3

1. •
   To erode.

   • The river is eating away at the river bank.
   • The battery acid ate away at the metal until a large hole appeared.
2. •
   To consume or use up, erode or wear away gradually.

   • The expenses ate away at our profits.
3. •
   To cause to feel uneasy, troubled, worried, guilty, or vexed; to bother about something.

   • Not confessing that I had stolen the money ate away at me until I could no longer sleep.