Thanks for writing to us.
Bump on the nipple in the post partum period is most commonly an infected mammary gland
duct. This is mostly treated with the help of antibiotics and maintaining a good hygiene. You need to consult your gynecologist for prescription of proper antibiotics. Do continue to express milk from this breast irrespective of the infection.
I hope this information has been both informative and helpful for you.
Dr. Praveen Tayal