What is the meaning of "va'Tischalchal ha'Malkah"?
Torah Temimah citing Megilah 15a #1: She became a Nidah 1 .
Megilah 15a #2: She needed to move her bowels (refer to 4:4:1:1*).
Esther Rabah (8:3): She was pregnant, and miscarried.
Rashi (15a): Her innards dissolved. Maharsha - Chil is an expression of fear - "Chil ka'Yoledah" (Yirmeyah 6:24). Since it is doubled (Chalchal), Chazal expounded like Chalulim and holes, from which come Dam Nidah or excrement.
The Gemara (Megilah 15a) expounds that she became a Nidah, or she needed to move her bowels. Why does the Megilah hint to this?
Ohr Chadash: Foreign powers overcame her, to hint that powers of Tum'ah come to rule over Yisrael.
Refer to 5:4:3:13.
Chavrusah citing Michtav Sofer: The two opinions argue about the sin for which the decree came. If it was for bowing to the image (refer to 4:1:1:1*), she became Nidah; idolatry is Metamei like a Nidah (Shabbos 83a). If it was due to benefit from the party, she needed to excrete.
Did she make a Shali'ach to remove Mordechai's sackcloth?
Vilna Gaon: No. Mordechai should remove it and come to talk to her. She thought that he fears to tell her via a Shali'ach.
Malbim: She sent garments to put over his sackcloth, so the sackcloth will not be seen, and he may enter Sha'ar ha'Melech.
Why didn't Mordechai accept?
Vilna Gaon: He did not want to refrain from his sackcloth even for a moment.
Malbim: He did not want to refrain from supplicating even for a moment. That would be like abandoning trust in Hashem and relying on human help.