I have a pain in my right armpit that radiates across my breast. i was checked by my gynecologist who found no lumps or swollen lymph nodes.

Muscle strain: This most likely sounds like a muscle strain. Breast cancer generally does not cause pain, so the type of symptoms you are describing usually come from either a muscle strain, or bruising if there has been any trauma to that area. It could also be fibrocystic breast disease but that would more commonly be tenderness in both breasts. You could try a course of ibuprofen for a few days.