"All the perfumes of Arabia will not sweeten this little hand." Why did Lady Macbeth say this? What does this tell the doctor about her problem?

L. Macbeth is referring to when she had Duncan's blood all over her hands. She had left the blood from the daggers with the sleeping guards. L.Macbeth is suffering from flashbacks alluding tomuch of the play. Her conscience is bothering her. She says that nothing, not even perfumes of Arabia, can take away the stench of death on her hands.(or aleve her conscience)

Nothing in the world could remove the stain of Duncan's death