I am a bit concerned about my bowel movement lately. my stool have changed to a ball-like shape x 6wks. its not hard and i usually go once a day.

More fibre: It sounds like you just need a bit more fibre in your diet.There's no blood, no constipation, and the stools not hard - if it were, i'd suggest better hydration. So, add whole grain breads and cereal, fruits, and vegetables. You could try a bulk laxative, such as fibre con or equivalent - not to help you move your bowels, but to add bulk and consistency. Good luck.