1)
Why does it say "va'Yhi Acharei Kol Ra'asech"?
1.
Radak: After all your evil, you are like you were initially ? naked and lacking everything.
2.
Malbim: Achaz was stricken in many different ways. Had he remembered that there is Elokim who judges and oversees, he should have repented! He increased to sin ? "uv'Es Hatzer Lo va'Yosef Lim'ol ba'Shem Hu ha'Melech Achaz" (Divrei ha'Yamim II, 28:22). The more than Hashem struck him, the more that he sinned.
2)
Why does it say "Oy Oy Lach"?
1.
Rashi citing Targum Yonasan: Woe to you that you sinned, woe to you that you did not repent!
2.
Radak: You should say 'woe' many times. You lost many good things via your sin!
