What is the significance of the words "Vayifen Par'oh ... "?
Targum Yonasan It means that Par'oh defecated 1 and went home.
Oznayim la'Torah: When Par'oh saw the devastation 2 that Makas Dam caused in front of his eyes, overcome with fear that he might be unable to resist any longer and capitulate
What are the implications of "Gam la'Zos"?
Ramban #2: He took notice neither of the sign of the staff nor even of the plague of the water turning into blood - which ought to have served as a warning that Hashem had now begun to strike him.
Seforno: He was not even impressed by the fact that his magicians were unable to perform what Moshe and Aharon had performed. 3