Hi, The most common causes of stammering are as follows: - Stress causes old thoughts to prevail over the present and can cause stammering and many other problems. - Anxiety is about the future wherein the person is worried about what can occur and thus the thought process becomes fragmented reflecting in stammering, the flying thoughts as you have mentioned. Hence many a times the following things help as you have already consulted so many doctors at Chennai and Coimbatore. I would advise you to consult a Psychologist or Psychiatrist for clinical evaluation which may help you the best. Also, have an opinion of a speech therapist who will help for identifying the problem and treat you accordingly. Purposeful changes by avoid the factors that increase your stammering can help you the best. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, General Surgeon