This was a book I was reading years ago and I can't remember anything that would let me google it--no character names, no author name, no title, just a lot of plot.

It was young adult science fiction. It was set in a town and a teenager had just died. There was a line about how the character's grieving girlfriend had messed up her makeup so she looked like a raccoon like people should be sad for her instead of the dead boy. Anyway the main character got these "shots" which he wasn't supposed to talk about because it was considered private, only at one point it came up in conversation and the girl he was talking to had no idea what it was. Thus the parents had convinced him that (a) everyone got these shots and (b) it wasn't something talked about, so that he'd never let it slip and get funny looks. These shots sucked because he got them once a month and they made him sick afterward.

Fast-forward and somehow MC finds out that he's actually an alien. The shots are designed to turn him human. The boy who died, died because the shots don't play well with puberty. MC finds out he now has to get the shots once a week, which is gonna suck exactly four times as much as having them once a month.

I don't remember if I finished the book or put it down without finishing. If I finished, I don't remember how it ended. Does anyone know what I'm talking about?