Buffy hadn't been lying when she told Heidi that she felt like a chicken running around with it's head cut off. Between trying to stop people from drinking the water (and they weren't even in Mexico), figuring out a way to stop the looming Apocalypse, and tending to those that were already sick, Buffy was more than thankful that she had Slayer stamina.
She hadn't spoken to Jack in a long time, but she wasn't going to let that stop her from saving his life. What had happened between the three Rangers was trivial in comparison to this, and she would push it aside, most definitely.
"Jack!" she called through his door, trying the knob and finding that it was open. She could've kicked it down, sure, but she wanted to save all of her strength for something a little more important.
"Jack?" She made her way towards his slumped figure, feeling a strong sense of deja vu hitting her as she knelt down beside him. "Hey, come on. You have to stay awake." She reached out and began to try and sit him up. Lifting and moving him wasn't an issue, but she wanted to make sure not to hurt him.