Do the cat/cow stretch. Get on all fours, with your arms straight and your hands directly under your shoulders; your knees hip-width apart.

Hello friend Your upper back pain is directly related to your long sitting. Do upper back strengthening exercises,you ll definitely feel better.

good evening ,your problem is ergonomical due to bad posture and life style which can be corrected with some life style changes

Yes, the problem is very serious as it is related to your work, as truly said that should go away with regular exercise but that will only be a solution to half of your problem. the complete problem will go once you STOP DOING WORK (THAT IS TOTALLY IMPOSSIBLE AND INSANE). SO , to make it more of practical I add , STOP DOING THE WORK THAT YOU ARE DOING LIKE NOW. that is you need to learn proper posture for doing your work and how to manage your day long work so that you can be healthy. A bit of posture management, a bit of work-space management mixed with working routine and slowly mixing basic exercises (if not hitting a gym) and that's the recipe to be a healthy you.

Hello..... That means you acquire improper posture while working...so just practice to sit straight with with erect spine... Do yoga, exercises which eases your back pain... Take rest... If pain is persistent you can take one or two painkillers... Consult orthopedic surgeon if it becomes severe....