sway (from) side to side
To continue moving, swinging, bending, tilting, etc., slowly in one direction and then back in the opposite direction. The structure swayed from side to side, threatening to topple at any given minute. Everyone in the crowd was swaying side to side in time with the song.
sway from side to side
to swing or bend from one side to the other. The car swayed from side to side as we started out, indicating that something was seriously wrong. He swayed from side to side with the rhythm of the music.