As your physiotherapist to observe your posture first to see what is abnormal in your posture
then ask him the correct posture so you can adopt it while sitting infront of computer, also do the excercises that your physiotherapist taught you ( Do them every 30 min). relax you reslf as much as you can , and be cool because nervous increase neck pain
also use a hot back applied while you are sitting on you office ( applied for 15 min)