I have fibrocystic breasts but can feel a strange lump that feels ike a hard long string / cord like at the bottom of my breast. what could it be?

Likely b9 but see md: Likely this is nothing significant with your history of sense breast tissue, however if this is something new and it persists or is worrisome to you then I should get evaluated by your regular doctor or gyn. If u are 40yo or older you might consider getting a mammogram or ultrasound. Discuss next steps with your regular doc.

A few possibilities.: Given your age and history you need a physical exam and imaging of your breast. While this is most likely benign, you want to be assured this is not something more serious. A simple exam with a mammogram and likley ultrasound should easily confirm the diagnosis.