I don't feel any lump just pain only when pushing on nipple could it be cancer?

Pain is not a common. Symptoms of cancer, but it calls your attention, and then the doctors may do other things that detect cause, or even cancer in a part of the breast. The nipple-aroela complex is the most sensitive portion of the breast. The safe call is to always get something that bothers you seen by someone with more experience.
Maybe. I don' t know how old you are, whether you are breast feeding a child, and this and other factors make a difference. However, if you are having pain anywhere in the breast, including around your nipple, you should see a health care provider.