AKs flops TPTK and runs into aggression post flop

[McNeese72]

Very early on the table (only 10 hands or so) so no accurate reads on the villain other than he hasn't done anything crazy that I've seen.

PokerStars 0.50/1.00 Hold'em (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is CO with K[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/club.gif[/img].
<font color="#666666">5 folds</font>, MP3 calls, <font color="#CC3333">Hero raises</font>, <font color="#666666">3 folds</font>, MP3 calls.

Flop: (5.50 SB) 6[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP3 bets</font>, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">MP3 3-bets</font>, <font color="#CC3333">Hero ??? </font>

Okay, heads up against an unknown who donks into me and then likes his hand enough to 3 bet, pop it again??? Or call and call down unimproved.

Doc