Since a few months, my mother is having stomach pain in the upper left side or in the center of her abdomen that comes and goes. she always feels bloated/swelled often & she sometimes feels nauseous. what is the likelihood of cancer? possible causes?

Constipation can cause the symptoms you are describing. Not sure how old your mother is but, assuming these symptoms are new, she probably should be examined by her doctor. She may need to see a stomach doctor to rule out other causes of her symptoms. Cancer is just one possibility-there are certainly benign causes-but you want to get her diagnosed and treated regardless of the cause. Good luck!

It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. The description you provided is too vague to suggest a diagnosis. It would be prudent to see a doctor. Wish you and your mother good health!