GNAWING

To bite something persistently, especially something tough.

"The dog gnawed the bone until it broke in two."

To produce excessive anxiety or worry.

"Her comment gnawed at me all day and I couldn't think about anything else."

To corrode; to fret away; to waste.

The process by which something is gnawed.

"the gnawings of mice"

A sensation of being gnawed.

(of pain or hunger) severe or intense