3/6 - I want to call with 3rd pair (smallish pot)

[wiggs73]

Villain is kitty97 who is very aggro. He's 3bet me a few times over the past few minutes and I have folded every time.

PokerStars No-Limit Hold'em, $6 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB ($600)
UTG ($377.60)
MP ($688.65)
CO ($467.45)
Hero ($850)
SB ($603.10)

Preflop: Hero is Button with 7[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">3 folds</font>, <font color="#CC3333">Hero raises to $24</font>, SB calls $21, <font color="#666666">1 fold</font>.

Flop: ($54) 6[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, Hero checks.

Turn: ($54) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $42</font>, Hero calls $42.

River: ($138) K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $126</font>, Hero


Is this a bluff often enough to call?

I guess our recent history has me a bit confused as to what his range is here. He's been 3betting me quite a bit, so I figured he would here with pairs 99+, AK and the like. So idk if this maybe a small PP turned into a bluff or a turned draw that's firing 2 or if I just want to be a callbox for no good reason.