1. without general examination it is not accurate to comment on the subject, because sometimes source is some where else also like in chest wall muscles,ribs, or spine. If you think it is a cyst
, or a irritated gland it will require a doctor's examination and prescription drugs or surgical intervention.
2. It is advisable always to see a doctor if you discover a breast lump, who might do simple fine needle aspiration with syringe to confirm whether it is harmful or harmless (if required).