On A Daily Basis I Seem To Get Very Sleepy,

On a daily basis I seem to get very sleepy, tired, my neck gets very tight, my back gets tight, my head starts aching, I drink plenty of water, I try walking around, I try to keep myself moving around but I still just want to lay down and sleep.
What is wrong, I go to the doctor and they tell me nothing is wrong all vital, blood work is normal and I am just stress out. Please give me an answer.