What Causes Recurring Neck Pain?

every other month or so i get major neck pain from the upper neck to betwwen the upper shoulders. it is very immobilizing and painfull. usually it occurs during my weight lifting routine but sometimes i wake up with it in the morning. I have been like this for 3 years. each episode lasts 3-5 days. sometimes i will be fine and then i feel a snap or crack that begins the pain.