my 2 year old cries hysterically for nap and bed

My 2 year old son has always been a great sleeper.  Naps 3 hrs a day with no hesitation going to sleep.  Bedtime was a breeze as well.  Approximately 3 weeks ago for no apparent reason he started crying hysterically when I placed him in his crib for nap as well as bedtime. This behavior happened abruptly.   I make him scream it out and he eventually falls asleep.  I can't understand why he is not adjusting back to his normal behavior.  Everyday the same thing with no improvement.  I am very scheduled and determined to let him self sooth but he is just not shaking this behavior.  Please help.  His screaming at night varies from 10 minutes to 4 hours depending on the night.  It is affecting my older sons sleep.

[Kevin Kennedy, Ph.D.]

To be frank, there's not much I can offer you. You are handling it fine and I would continue along the path you are taking. This will have to run its course, and it's important not to interrupt the bedtime routine that you have established. The nap time is rather long and it may be part of the problem. In other words, it may be that he is not sufficiently tired after such a long nap. It's hardly ever a good idea to wake a child from sleep, but you might want to consider shortening those naps.