What Causes Stiff And Locked Neck While Travelling?

I have a stiff neck and while travelling it gets locked at times. My back starts paining after midnight and once I am up from bed in the morning, it subsides slowly. I am unable to stand for a long time as I start having a pain on the lower left hand side of my back. (I have hyperthyroid, and have had two surgeries for removal of my uterus and cystic ovaries). Please suggest