Two pair counterfeit on river against maniac

[MikeyPatriot]

READS: No stats, but I played this hand w/villain and have watched him run up a stack.

PokerStars No-Limit Hold'em, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

MP ($134.15)
CO ($149.70)
Button ($141.95)
SB ($102)
Hero ($102.95)
UTG ($168.80)

Preflop: Hero is BB with K[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, CO calls $1, <font color="#666666">1 fold</font>, SB completes, <font color="#CC3333">Hero raises to $7</font>, CO calls $6, SB calls $6.

Flop: ($21) 2[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets $20</font>, <font color="#CC3333">CO raises to $142.7</font>, SB folds, Hero calls $75.95 (All-In).

Turn: ($259.65) 4[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players, 1 all-in)</font>

River: ($259.65) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players, 1 all-in)</font>

Final Pot: $259.65

Results in white below:
Hero has Kd Kc (two pair, kings and fives).
CO has 6d 5c (three of a kind, fives).
Outcome: CO wins $259.65.

PokerStars No-Limit Hold'em, $1.00 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

SB ($108.60)
BB ($324.45)
UTG ($138.95)
MP ($100)
Hero ($100)
Button ($164.55)

Preflop: Hero is CO with 6[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises to $4</font>, <font color="#666666">1 fold</font>, SB calls $3.50, BB calls $3.

Flop: ($12) A[img]/images/graemlins/spade.gif[/img], J[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, BB checks, <font color="#CC3333">Hero bets $11</font>, SB folds, BB calls $11.

Turn: ($34) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero bets $27</font>, BB calls $27.

River: ($88) 7[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $100</font>, Hero

I almost puked when I saw this river. After some thinking, I couldn't figure out any hands he has that make sense here. AK-AJ bet or raise before the river. JJ raises PF, 66 is unlikely as I have one of them. A backdoored 7 would be so so sick. Thoughts?