Hello shanmugamkmu,
Welcome to the forum. Most of the people working on computers are affected with these symptoms. It is your sedentary working hours, your posture while you work that is causing you trouble. Get a comfortable seating arrangement for yourself. Your back should be straight and the chair should be supporting your back. Shoulder and
neck pain are indicative of your incorrect posture. You can use some muscle spray or pain killers along with dietary supplements ( vitamin B, calcium and minerals ). It will give temporary relief.
You should also take breaks between your work whenever you can. When you feel any
stiffness in the neck or shoulder, start a few neck exercises and swing your arms to feel better. Avoid being seated for very long, continuous hours.
You can consult a physiotherapist and do shoulder and neck exercises. Also consult a doctor and get a radiology done to study any defect in your
vertebral column. At home try to get a comfortable
stress free sleep. Make sure your mattress is very comfortable, if not change it.
Have a good day, take care.