I am 22 male .I am currently in Delhi preparing for exam since last 2 months I have been facing alternate cycle of diarrhoea and constipation .I have lost my appetite considerably. I don't find blood in my stool .neither my stool have blacks appearance .I do fail nauseated at times and there is feeling of discomfort in left abdomen as a pain or cramp .I am not able to empty bowel properly .I go 3 time a day .I have consulted a local physicians and he told me to have USG whole abdomen ultrasound .which was normal. I have been reading in Google symptoms of colon cancer .should I be worried.