Hi, The causes I can think about are as follows: * Burning sensation are most suggestive of nerve problems like pinched nerve in the neck * Trigeminal neuralgia * Muscle spasm in right side of neck * Cervical spondilitis Ultrasound and endoscopy do not help in such diagnosis hence turned out to be normal. You need the following: - Clinical examination of the neck muscles on both sides to compare - Get started with anti-inflammatory medicine with painkiller properties like Ibuprofen - Request for prescription based muscle relaxants - Local Rubefacient liniment for warmth and muscle relaxation - Neck support in a collar All these will help to have proper relief. Also, get ear checked out to rule out any local problem. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, General Surgeon