At night, my back will get warm in one spot. It is uncomfortable to the point that it will wake me up. what is the possible problem?

It is possible that you have a disk bulge in your spine, where the soft cushion between your vertebrae herniates or pushes out and against your spinal cord and spinal nerves, causing the sensations you are describing. Do you have back pain? Where in your back do you feel this sensation? It is possible for the pressure against your nerves to cause discomfort or pain in other parts of your body, as well, where the spinal nerves send and receive signals. So, do you have pain in other areas of your body?

Go to a chiropractor and he will probably suggest an MRI to see your spine.

(I am not a doctor.......yet :) )