Doc, why i got pain on my back each morning i wake up?. it feels like i slept over hard surface through the night. (i have a good spring bed).

Strain: Most likely, as you are young, your back pain is from muscle strain. Try abdominal strengthening exercises. Try sleeping on a more firm mattress or laying on your side when sleeping. There are other causes of back pain as well like trauma, arthritis, disk disease and more. If the pain doesn't go away, get a medical evaluation. I hope you feel better soon.