Well, without a clinical evaluation it would be difficult to determine the cause of your symptoms. Possible causes of neck/ back pain include postural issues, neuro-muscular causes such as muscle sprain, nerve impingement, injuries to muscles/ ligaments etc. inflammations, fractures/ dislocations, bone bruise, referred pain from other regions, micronutrient deficiencies etc. While fractures and dislocations would be ruled out with x-rays other possibilities may need to be evaluated for. I would recommend acquiring a straight back posture while sitting. Back and postural supports may be useful for the purpose. Physiotherapy may help improve the strength in the back muscles and may be helpful in symptomatic relief. If the symptoms do not seem better with the recommended measures, you may seek a review with your treating doctor for a detailed evaluation and suggestion of an appropriate management pan.
Hope this is helpful.