Why does it say "Me'ai Me'ai"?
Radak: People who lament are wont to double their words. The same applies to "Roshi Roshi" (Melachim II, 4:19). The Navi screams from pain of his innards. I am gripped with trembling and pain due to the evil that comes to us.
Malbim: The innards are aroused only via natural fear and agony that man's choice cannot overcome. The heart is aroused by desire, and clamors about something that man can change - to bring it close or distance it.
What is the meaning of "Ochilah"?
Rashi: It is an expression of Chil 1 and trembling.
Radak: "Chil ka'Yoledah" (6:24, i.e. trembling. - PF)
What are "Kiros Libi"?
Rashi: They are the supports of my heart.
Radak: This is a metaphor, for the heart has walls and a cavity.
What is the meaning of "Homeh Li Libi Lo Acharish"?
Radak: If you will say that I can scream sometimes, and be silent sometimes - I cannot, for constantly my heart clamors.
Malbim: I cannot silence my heart, for I caused and still cause the evil on myself. After they saw that the cities [of Yehudah] were destroyed, and Nebuchadnetzar exiled Yehoyachin, Tzidkiyah rebelled against him a second time and blew the Shofar to fight Bavel, even though he should have known that he will not succeed. My heart clamors - why will they fight?!
What is the meaning of "Shamat Nafshi"?
Rashi: [My soul heard] in back of the curtain the tidings of Shofaros of war.
Radak: It says "my soul", and not my ears, because his ears did not hear yet. The enemy did not come yet. My soul heard via Nevu'ah; due to it, I cannot be silent.
Why is it written Shamati, and we pronounce it Shamat?
Radak: These are the same. His hearing is hearing of the soul.