I Am Having A Lot Of Pressure At The Base

I am having a lot of pressure at the base of my head into my neck. This happens mostly when I am sitting or driving. I feel as though my neck is getting stiff. Also when I sleep at night, the joints in my arms get stiff and painful to move when I awaken. I feel that these discomforts are coming from my upper back but I don't know what exercises I should be doing.