Worried i might have colon cancer due to change of bowel habbit. my habbit return to normal for a few weeks then go of cycle then return back to normal. never a persistent change. been diagnosed with ibs after full blood test came back clear ?

Unlikely cancer: at the age of 30, colon cancer is extremely rare. The patient population in which cancer could be possible is typically those with a VERY strong family history of colon cancer, those with inflammatory bowel diseases (Ulcerative colitis, Crohn's disease, etc). Cancer typically causes what we call "constitutional symptoms" which include but are not limited to night sweats, fevers, weight loss.

IBS: Colon cancer is not excluded by a blood test but your symptoms remain consistent with irritable bowel syndrome. A gastroenterologist is best qualified to evaluate and advise you. Colonoscopy may be recommended.

Typical IBS symptoms: Colon cancer rarely causes any change in bowel habits. This sounds like pretty typical irritable bowel syndrome and I see no reason to be concerned about cancer. Discuss with your GP.