He walks and then drives around for what seems like forever, trying to find a pay phone that actually works, before deciding that his best bet is probably breaking into the infirmary again and using the phone there. The nurse leaves for the night and the place is empty, so Sammy must have done quick work and gotten Leslie to wake up. The kid's awfully good.
He dials Caleb's number, letting the phone keep ringing dully against his shoulder. He doesn't let himself get impatient; this is too important, Sammy could be in danger too. He keeps the receiver in his hand, kicks off his boots, and stretches his muscles. The phone is still ringing. He wishes he had knives and a whetstone, or their guns and some oil. The line disconnects, so he dials again. In a drawer he finds a blank notebook and a pen. He writes down everything that's happened, trying to keep things in order. It makes things a little clearer in his brain, and by the time Caleb finally picks up, he's able to give him the whole story, straight, no revisions, and ask the right questions. Caleb being Caleb, of course he has to answer in a long, roundabout way, starting with the time he took one of these things on when he was not much older than Dean, and how he'd learned something very important from that encounter, and "there are things you need to know, Dean, before you go after it, and I'm not just talking about the demon and its powers, but things you need to know about yourself before you've got a shot at bringing it down. You need to know if you're afraid of the right kind of thing." His voice gets quiet before he finishes, "No shame in not being the one to defeat it." But he's not about to let some fucker in a lake - it's got to be living in the lake - get the better of him and keep hurting whoever it damn well pleases, so he just says his thanks and gets off the phone.
It's late, past midnight by the time he leaves the infirmary, and it's no work at all to sneak into Sammy's cabin, pick him up from where he's sleeping on the shower floor, and carry him back to bed. Sammy's cheek is waffled from being pressed against his thermal sleeve, and he runs gentle fingers over its round softness. He zips up the sleeping bag before heading tiredly to the Impala.