Why does it say "Shakadti"?
Rashi: I contemplated by myself, and I am like a lone bird on the roof, which dwells alone without a mate.
Radak: Shekidah is constant engagement in a matter, like "Shav Shaked Shomer" (127:1), "Lishkod Al Dalsosai" (Mishlei 8:34).
Malbim: After great efforts, also this decree (refer to 102:7:4:2) was lifted, and I was able to dwell in the city, but not in a house, rather, like a lone bird on the roof. So I needed to live on the corners of the roof, isolated.
Why does it say "Boded"?
Rashi: It dwells alone.
Radak: I was constantly in Galus, here and there, and everywhere I find myself alone among a foreign nation, like a bird separated from its colleagues, and it is alone on the roof. So it is as if I dwell on the roof, even though I am in a house, since I am not in my land.