[50NL] Q9o...BvB, raise river?

Villain is 26/26 over 25 hands.

PokerStars - $0.50 NL (6 max) - Holdem - 5 players
Hand converted by PokerTracker 4

SB: $31.39
Hero (BB): $50.00
UTG: $19.56
CO: $31.50
BTN: $47.95

SB posts SB $0.25, Hero posts BB $0.50

Pre Flop: (pot: $0.75) Hero has Q:diamond: 9:club:

fold, fold, fold, SB raises to $1.50, Hero calls $1.00

Flop: ($3.00, 2 players) 9:spade: J:club: 4:diamond:
SB checks, Hero bets $2.25, SB calls $2.25

Turn: ($7.50, 2 players) 3:heart:
SB bets $2.50, Hero calls $2.50

River: ($12.50, 2 players) Q:spade:
SB bets $5.50, Hero ???

I'm not sure about betting the flop here, I bet to protect my hand and am just happy to take the pot down there. I don't think I can fold turn for such a small bet either when I likely still have the best hand.

I don't really know what villain is trying to rep w/ his line so I'm not sure what his range is in this spot either.

Raising too thin?

I'd bet about 1.25-1.75 on the flop. You obviously can't fold a hand this high in your range for 1/3 the pot on the turn. When he bets such a timid size on the river I think you can raise here. I wouldn't go a crazy size, something like 14.75 would be sufficient.

call and win at showdown a lot. I don't like raising river given that he's sat with only 60bb - if he was fullstacked then raise (small) away.

You don't know are you the winner in this hand or not, so for my opinion it will be better if you only make a call. I don't think that he has set or maybe straight, but in situations like this it would be better if you only call.

I agree that a call is the right move on the River. You could be behind here but you have to make the call given the bet size. The size of the bet makes may a bit suspicious but you have to call this.