Pain or burning sensation in breasts is called mastodynia or mastalgia.
There are many causes of soreness of breasts,premenstrual syndrome and pregnancy being one of them.Other
important causes are fibrocystic breast disease,ductal ectasia,mastitis(inflammation of
breasts),galactoceles,benign and malignant pathologies of breasts,referred pain from liver or musculoskeletal
system,arthritis of the ribs,costsochondritis and inflammation or sprain of pectoralis muscle.
Since you are having a past history of breast lumps,so these also need evaluation.What is the other ingredient
in the composition of your prilosec medicine?
I feel that an examination by a gynecologist and a mammogram will be the best.Till that time,apply some warm
compresses on the breasts and take some over the counter pain reliever(analgesic) like ibuprofen or
Hope it helps.Take care and pls do keep me posted if you have any additional queries.Kind regards.