According to the symptoms you describe (clicking noises, popping noises, strange feelings in the chest, thoughts about a brain tumor …) you might be experiencing hypochondria. You can visit a dentist to look at your teeth and to diagnose TMJ. You may also see a cardiologist for the chest and heart for diagnostic procedures, and an ENT-specialist for your ears. If all of the examinations are normal, you might consider consulting a mental health professional about feelings of constant illness. Psychotherapy can help ease the anxiety of feeling unwell, and/or alone.