I have a lump in my boob and its as big as a grape...?

Breast Lesion: This is likely a benign process given your young age, but given that rarely these may still represent a malignancy in a young person. See your physician for an exam and also a diagnostic ultrasound (or mr, if indicated). Often that can help guide treatment. Common benign processes in your age group are fibroadenoma, fibrocystic changes, intraductal papilloma, and fat necrosis among others.

FIBROADENOMA : An overwhelming majority of breast lumps in teenagers are benign tumors, called fibroadenomas. I recommend that you schedule an appointment with your primary care doctor. They will likely order a painless test (an ultrasound) and refer you to a breast specialist to seek out their opinion.