You risk being killed if you draw attention to yourself. You may have something they want or of value to them. Drawing attention to yourself decreases your chances of survival.
"The stomach alone was aware of the passage of time."
As time passes the hungrier a person becomes. Time reminds you to eat. It is important to live. He must live for his father. He must live to tell his story.
"The dentist pulled out my crowned tooth, with the aid of a rusty spoon."
The dentist used a rusty spoon to remove a tooth. Elie could have gotten tetanus from the rusty spoon. Tetanus can kill within 4 days of infection. A few symptoms are muscle spasms and fever.
Elie was scared after his leg surgery. He was unable to feel his leg with fear that it may have been amputated. He asked the doctor about his leg and was reassured that he would be recovered in a fortnight.