When do you ice and when do you use heat?

 I've been having a problem with my neck (right side) and upper shoulder.  Not constant, but when it hurts, it hurts.  Woke me up at 4:00am last night and I put ice on it and went back to sleep.  It was fine in the morning.  I iced it after working out this morning.  But sometimes heat feels good on it too.  How do you know when you should use ice and when you should use heat?

Jan

I have always been told alternating ice and heat or fine based on how they make you feel. I've also heard you ice it in the beginning for swelling; then use heat for comfort after the first 48 hours.