I'm not a doctor, but I can suggest some possibilities to consider. Chronic upper back pain in a child, accompanied by vomiting, may be caused by a variety of issues, which should be evaluated by a healthcare professional for an accurate diagnosis. Here are some potential causes:
1. **Musculoskeletal Issues**: Poor posture, muscle strain, or spinal issues like scoliosis could contribute to back pain.
2. **Infections**: Conditions like a kidney


