1)
Before, Amatzyah heeded the Navi. Why did he now get angry at him?
1.
Malbim: Now the Navi did not speak in the name of Hashem; he gave his own counsel.
2)
What is the meaning of "I know that Hashem counseled to destroy you"?
1.
'Rashi': If you will not take my counsel to go on the straight path, Hashem will give to you counsel to destroy you. He was counseled to fight Melech Yisrael (verse 17).
2.
Malbim: I do not speak on my own. I had a Nevu'ah that Hashem counseled to destroy you for this sin, therefore I counseled you to repent!
