I changed the name of Jealousy Kills for now, though I really like the title name. I had to think of how "Jealousy Kills" sounds to an agent, and thought they might get the wrong idea of the book. Once, and hopefully eventually, I get a contract for this book, I'll see if I can get my old title back.
Anyway, I re-did my 13 lines. Let me know how it is, compared to the others, and anything else you think I should know.
Also, let me know which title you like better: WITHIN or Jealousy Kills.
Justin Adams rocked his leg up and down anxiously as he waited for Dr. Marks in the waiting room. A sweat broke out above his eyebrow and he wiped it off. He looked at a lady across from him, noticing how she rocked back and fourth as if she belonged in a mental institution, and she held her purse to her chest protectively. She gave Justin a startled look, and he backed up, suddenly scared she’d jump out of her seat and attack him. What am I doing here? Justin thought, realizing this was the last place he ever thought he’d be. This place is for Psycho’s. I’m no psycho, right? The woman looked left, then right, then she burst into tears. A door behind her opened, making them both jump.
I wouldn't say he rocked his leg up and down. Because at first I thought he was rocking, which made him sound crazy. But then I figured out you meant he shook his leg nervously. It's a habit I'm guilty of when I'm waiting at the DMV, but for me, it frustration rather than nerves causing it.
I liked the bit with the crazy lady. It made me laugh. You don't capitalize the P in psycho, though, unless you're talking about the movie. Just so you know.
Otherwise, I like it! I think it starts at a good spot, and give a window in to what Justin is thinking as he's waiting for the doctor.
I read it but not sure what to say. It gives a clear picture of your MC and something about his problem. If anything you might try condensing the part about the woman. That seems to drag a tiny bit. I don't mean necessarily take out anything just say it with less words. Except for maybe her bursting into tears, not sure if that does much for it with what you got there anyway, and feels cliche-ish.