This is a medical question of type : symptoms 
 What are the symptoms of Chronic Fatigue Syndrome (CFS) ? 
 Chronic fatigue syndrome can be misdiagnosed or overlooked because its symptoms are similar to so many other illnesses. Fatigue, for instance, can be a symptom for hundreds of illnesses. Looking closer at the nature of the symptoms though, can help a doctor distinguish CFS from other illnesses.
  Primary Symptoms
  
As the name chronic fatigue syndrome suggests, fatigue is one part of this illness. With CFS, however, the fatigue is accompanied by other symptoms. In addition, the fatigue is not the kind you might feel after a particularly busy day or week, after a sleepless night, or after a single stressful event. It's a severe, incapacitating fatigue that isn't improved by bed rest and that is often worsened by physical activity or mental exertion. It's an all-encompassing fatigue that can dramatically reduce a person's activity level and stamina.
  
People with CFS function at a significantly lower level of activity than they were capable of before they became ill. The illness results in a substantial reduction in work-related, personal, social, and educational activities.
  
The fatigue of CFS is accompanied by characteristic illness symptoms lasting at least 6 months. These symptoms include:
  
   - increased malaise (extreme exhaustion and sickness) following physical activity or mental exertion
   - problems with sleep
   - difficulties with memory and concentration
   - persistent muscle pain
   - joint pain (without redness or swelling)
   - headache
   - tender lymph nodes in the neck or armpit
   - sore throat
  
  Other Symptoms
  
The symptoms listed above are the symptoms used to diagnose CFS. However, many CFS patients and patients in general may experience other symptoms, including:
  
   - brain fog (feeling like you're in a mental fog)
   - difficulty maintaining an upright position, dizziness, balance problems or fainting
   - allergies or sensitivities to foods, odors, chemicals, medications, or noise
   - irritable bowel
   - chills and night sweats
   - visual disturbances (sensitivity to light, blurring, eye pain)
   - depression or mood problems (irritability, mood swings, anxiety, panic attacks)
  
  
It's important to tell your health care professional if you're experiencing any of these symptoms. You might have CFS, or you might have another treatable disorder. Only a health care professional can diagnose CFS.
  What's the Clinical Course of CFS?
  
The severity of CFS varies from patient to patient. Some people can maintain fairly active lives. For most patients, however, CFS significantly limits their work, school, and family activities for periods of time.
  
While symptoms vary from person to person in number, type, and severity, all CFS patients are limited in what they can do to some degree. CDC studies show that CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis, heart disease, end-stage renal disease, chronic obstructive pulmonary disease (COPD), and similar chronic conditions.
  
CFS often affects patients in cycles: Patients will have periods of illness followed by periods of relative well-being. For some patients, symptoms may diminish or even go into complete remission; however, they often recur at a later point in time. This pattern of remission and relapse makes CFS especially hard for patients to manage. Patients who are in remission may be tempted to overdo activities when they're feeling better, but this overexertion may actually contribute to a relapse.
  
The percentage of CFS patients who recover is unknown, but there is some evidence to indicate that patients benefit when accompanying conditions are identified and treated and when symptoms are managed. High-quality health care is important.