I feel extremely tired from time to time. This tiredness lasts for 5 days then departs! It comes to me twice a month at least. The rest of the time I am normal and perfectly fine. During this fatigue period, even my mood is not right and I am unable to think clearly. I have visited different doctors and all gave me many tests and concluded I am fine, although they felt very puzzled. The only thing was some kind of bacteria (helycobacter) was found in my stomach. This condition is greatly affecting my work, so I would greatly appreciate your advice.