Extract symptoms and complaints from this medical document. Return a JSON array or null.

Each entry:
- type: "chronic", "acute", "observation"
- value: (empty)
- summary: symptom description, e.g. "Head tilt to the right"
- timestamp: "YYYY-MM-DD" if date mentioned
- data: {"symptom": "...", "severity": "...", "details": "..."}

Only extract SYMPTOMS — things the patient experiences or displays.
NOT diagnoses (those go elsewhere), NOT imaging findings, NOT test results.
A symptom is something observable: pain, difficulty walking, head tilt, irritability, fever.

Document:
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