YA scifi

I read a book about ten years ago when I was in middle school, but I can't remember the title or author anymore. This is a YA scifi I believe. The main character is a boy whose story begins in the hospital. I don't remember how he ended up there, but the doctors find out upon examination that he has all sorts of unknown technology underneath his skin where his organs, muscles, etc. should be. He is kept there against his will, but somehow escapes. Agents are after him, but he meets a (goth, edgy?) girl who helps him learn how to hide from the law. They build a life together in a safe-house, fall in love, but he never tells her why agents are after him. At the end, the agents catch up to him, and she ends up getting caught in the crossfire and dying. He goes on the run again, and that's where the story ends. Any help would be appreciated! :)

Being by Kevin Brooks.

"It was just supposed to be a routine exam. But when the doctors snake the fiber-optic tube down Robert Smith's throat, what they discover doesn't make medical sense. Plastic casings. Silver filaments. Moving metal parts. In his naked, anesthetized state on the operating table, Robert hears the surgeons' shocked comments: 'What the hell is that?' 'It's me,' Robert thinks, 'and I've got to get out of here.' Armed with a stolen automatic and the videotape of his strange organs, he manages to escape, and to embark on an orphan's violent odyssey to find out exactly who--exactly what--he is"

That's it!!! You're a gem, thanks so much!!