Yes, she definitely was suddenly just THERE. Again, there might have been some other build up scene that was left on the cutting room floor, but for the viewers, a "huh, who is that" moment.
That said, the other nurse wanted her put in the break room to avoid the administrator making a huge fuss about it.
So here is MY take. The woman is a nurse, & able to get her hands on dangerous medication. So WHY, if she really wanted to kill herself, does she overdose in the middle of the hospital, with doctors, nurses, all over the place? I get she was upset about something, but seems she could have gone home, or into a bathroom, or even an empty hospital room. No, she does this where someone will quickly find her. Thus.......I am very leery of her. Could there be some reason she wanted to get JJ's attention? Or the other nurse? There just has to be more than just a despondent woman.
By the way, this actress was on American Idol, I think she won...no idea what category.