horrible 30 60 hands

[cocofrite]

4 handed on pokerstars
sb's just arrived, co seems solid

cutoff limps, sb completes, i check in bb with a7 offsuit

flop 554 two hearts
sb bets, hero raises (thoughts ?)

turn 9 no suit
sb checks, hero bets

river k no suit
sb bets, hero folds (thoughts ?)
does anyone ever fold flop here against unknown ?

i hate the way i played this hand (dumb agression in an unraised pot) and i dont understand his betting pattern (kx suited maybe)