I'm raising all in, my hand is forced by this turn bet. No way I'm folding when he's only really beating us with 44. Ok he can have AK, but it seems unlikely given he flatted pre and then donked the flop. And sure he can have K9 or even 89, but if so he won't keep his winnings for long.

He seems too fishy for me to be letting go of top two here. If we're beat, then be sure to note what he had and how he played it. In fact, do this if we win, too.