My left breast is sore, im 22, not pregnant not on period not on borth control, my grandmother died of breast cancer at 60, how do i check for it/what could be wrong?

Breast soreness: Statistically it is unlikely you have cancer, but you need to see your doc for a proper examination.

Get workup: Any change in your breasts warrant a workup. See your primary care doctor or ob-gyn. They will get a mammogram if concerned then proceed accordingly. Your family history means you need to get assessed rather than dismiss breast pain, swelling, skin changes, or discharge.

Not to worry: Breast pain may be a sign of cancer, however, breast pain is far more commonly due to benign processes. Cyclic changes in hormone levels are a common cause of breast pain. If this persists beyond a few cycles, i suggest you see your gyne for a breast exam. Having a 60 yr old g'mother w/breast cancer should not change your risks & at age 20 your chance of cancer is 1in a million.