Hello, The symptoms of depression (I think you mean sad mood), poor appetite, anxiety attacks or bouts of anxiety (panic attacks), fatigue, headache, poor concentration, with all medical evaluation being negative (I am making the presumption that it includes thyroid and haemoglobin) is suggestive of a mental health related ailment which is in all likelihood a Depressive episode. As a next step I would suggest that you seek a consultation with a psychiatrist near you. He is likely to conduct a detailed interview as well as review your medical documents and come up with a conclusive diagnosis. A combination of mediation and psychotherapy is likely to be well suited to your problems. Hence please visit a psychiatrist for further comprehensive assessment and treatment. Hope this helps you. Best wishes for your health and future.