I have noticed a small lump on the inside left of my belly-button. It doesn t pain, but my grandma and aunts have had a history of cancer . I wonder if it is a tumour. Also, could it possibly have developed due to the usage of electronic stimulator for weight loss . I tried them for a few days, though I know that they mimic nerve impulses to make muscles go into forced contractions, and don t really help to shed weight.