Nightmares

Wow, I think I might just die of exhaustion. I know I've been a mom now for 16 months and should be use to it by now, but Zack has always been a good sleeper until now. He goes to bed at his usual time, 9:15, and then we go to bed around 11:30. At 2:00 on the dot he wakes up screaming. I get up to see what's wrong, and he continues to scream. I change him while Paul runs upstairs to get some milk then I rock him, hoping he will fall asleep. He's calmed down a little so I put him back in his crib thinking he'll go to sleep. Boy, am I wrong. The screaming starts again the second I lay hime down and shut the door. We do the same thing with cuddling, but this time I feed him something other than milk. He thinks it's time to play, not sleep. It's as if he's just taken his nap. 6:00 rolls around and he's ready for his "nap". He is now off his usual schedule since he'll usually sleep until about 9:00 if he does this and then he wont take his real nap until later. I have to be up by 7:00 so I can shower and be upstairs ready to take calls at 7:30, so I don't get much more sleep. This has happened now about 3-4 times in the last couple weeks. I'm assuming that the reason he wakes up screaming is because he's having nightmares. I didn't think kids his age would have nightmares this often, but what do I know? Any ideas? This morning it was because he had a fever. I gave him a cool bath and gave him some tylenol, but it never really went away. Here I am trying to work and about ready to fall over with exhaustion. I am taking any advice if anyone is willing to give any on how to keep my kid who use to be a really good sleeper asleep during the WHOLE night.