1)
Why was it in Sedeh Pelishtim for seven months?
1.
Kli Yakar (Lani'ado), citing Bereishis Rabah 54:4: This was one of many punishments due to Avraham giving seven lambs to Avimelech.
2.
Malbim: After seven months they realized that it is not chance, for chance does not persist constantly.