*Grunch*
I have been in this situation before too. I am guessing that villain had 4[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] or he made a set of 5's or 10's, and had put you on a high pair -- j's or better. Personally, at the limit you are playing your preflop raise looks fine. But at the flop, minus any reads, that raise from MP3 is concerning, and I would consider folding right then.