Here are your answers:
--This is a benign condition and usually responds well to treatment. It may go on to become a fibradenoma in some cases.
--Presently, you can try firm breast support, diuretics to reduce the water logging and analgesic-anti-inflammatory to reduce the tissue reaction and pain. Hormone supplements may be tried with some help.
--The cause is hormonal
leading to tissue reaction and water logging.
Hope this helps.