Call. The button has already shown that he's not folding for 2 bets, and there's a good chance MP2 already has you beat. The button could have either flush draw or a small 2 pair. It's possible MP2 has a smaller 2 pair, but judging from the play, I think it's more likely he has a straight or hit a set.

As for the unimproved river- reluctantly call (pot odds) and fold if the button raises when a club hits.