I was treated my mastitis but i can still feel a little bit mass on my left breast but no pain at all, i don't breast feed now how can i treat this ?

See your DOCTOR.: It is highly unlikely that this will develop into any other problem and it will likely resolve on its own with warm compresses and anti-inflammatories but it should be evaluated and followed by your physician. This could develop into an abscess or fat necrosis and may benefit from aspiration, drainage or excision if it does it resolve.

Mastitis: May be incompletely treated warm compresses time and if not progressing next few days will need to revisit physician.