Of course things weren't running smoothly on the inside, that much is obvious by the, as you say, constant need for changing his appearance and many characteristics of his personality.
But imagine being beaten as a child and constantly being called ugly, constantly being told you had a big nose, constantly being told you weren't good enough. That is going to have a long and damaging effect; any psychologist will tell you that. I believe he went through all the changes he did because he wanted to escape from those, what must have been awful memories as a child, I think he just wanted to erase that best he could, and the only way to do so was by changing his appearance. Unfortunately though, he was never happy with how he looked; but the media constantly calling him a freak amongst a whole host of other stuff wouldn't help.
The media, I think people underestimate them and just how powerful they can be when they want. I mean for gods sake the man was famous from the age 5 onwards, all the way upto his death at 50. He was the most famous man in the world. How on earth could he ever possibly live a normal life? That's what baffles me with some people, they expect him to be normal, despite living in the most un-normal circumstances you can imagine. He never had a childhood, he was playing in strip joints at 1, 2, 3am in the morning, then his brothers would bring women back to the room they shared and have sex with them whilst he was there. He never had birthday's, christmas or anything like that, and I think that's why he created Neverland. The place was just full of all the things he never got to do as a kid, and he opened that up to kids who, mostly, were underprivileged, or orphanaged, i.e. kids who themselves would never have a proper upbringing, he just wanted to help children. He felt comfortable around them, and that's probably why he spent to much time with them, becuase he was at ease. As he said in an interview (The Bashir one I think), adults would stab him in the back and many had ulterior motives, whereas kids just wanted fun, as did Jackson. Unfortunately a few of the kids parents saw fit to try and make money off his kindness, and so his downfall began.