What does the narrator mean when she says, "my conscience gets horribly pricked"?

oh-iwish-i'd-looked

#1

What does the narrator mean when she says, “my conscience gets horribly pricked”? Why does she feel like this?


#2

It means that she is feeling very guilty because she realises that she herself is responsible for her tooth decay. She also feels guilty at the thought of the number of sweets she has had in the past.