You are having depression from what it looks like. consult a therapist.

Hello Friend, Good that you are seeking a help here. All the mentioned symptoms are sign of anxiety and depression. Your mind may be always pre occupied with thoughts of either some past incidents or worry about future or about career or relationship issues. This will obviously cause negativity in all the activities you do, lack of concentration, low appetite, headache, fear etc. So don't hold on such emotional disturbance within you. Take a professional counselling support to assess your suitation and figure out the reason for your anxiety.