What has happened to Britney Spears?

Fame began for Britney Spears in 1998 when she wore pigtails and naughty schoolgirl dress- in "Baby One More Time". Since then, she has become her own industry, producing extremely high record sales. But recently the tables have turned. After her 2006 divorce to Keven Federline which also produced 2 beautiful innocent children, she hit the party scene and showed bizarre behaviour.

Something must have occurred to make this beautiful youthful 26 year old go from this....
To this.......

I do feel sorry for her as many people would wish to have what she is having yet she portrays herself as a very unhappy person. I guess you want what you cannot have!