The chronic duration of symptoms,predominance of gastrointestinal symptoms,normalcy of investigations go in favour of IBD
.(Irritable bowel disease).The exact cause of this disease is yet to be understood,but its true that stress
is implicated very strongly in this. Malabsorption
is another cause,so also is certain parasitic infections.Some dietery modifications may be tried such as cutting down on the carbohydrate
content of the food and increasing the fibre content.Psychotherapy
and stress related techniques have been found to be useful.But all said and done,there is no definite cure.This is a chronic condition and may stay all life time ,but it has no effect on the life expectancy.So,there is no need for worry and symptomatic treatment as and when required will suffice.