That's a hard one. On the one hand kids that age need to be acknowledged to feel secure but on the other hand if it's allowed to continue it'll get worse! Certainly find out what the parents do at home but I wouldn't let him get so worked up that he can't go back to sleep anyways. Maybe you cold try letting him fuss for 5 min. and then just poke your head in and let him know that you're still there but that he needs to go to sleep. I'd avoid picking him up or catering in anyway. If he continues, wait a little longer and then poke your head in again... And then ask for an Extra large coffee because so much for your break time!