What Causes Persistent Lump In Breast?

hi,iam sony 29 years old from last 8 years there is a knot in my left breast and its size is differ than right.it has become very loose from 1years i take homeopathy medicine but cannot cure completly last 4,5 days i feel pain in left one .i am mother of 2 children.please suggest me related to my problem.thank you