Based on the information it seems like there could be multiple reasons that are affecting your back. When you start a desk job, itâs a new position for your spine and itâs hard to maintain a correct posture for 6-8 hrs. Trunk muscles pays a huge toll any this leads to an imbalance and weakness, and pain.
You need to take multiple breaks during your work hours, after every 30 min stand up, stretch your back and talk 2 min walk. Keep all the screens at eye level, provide good support to your elbows while sitting. Use cold pack few times a day.
Next Steps
Make an appointment with a PT before it gets worse.
Health Tips
Try not to lift anything that weighs more than 5kg.