What we are seeing in the picture is most consistent with a blocked areolar gland (also called a Montgomery gland) or a small superficial follicle infection, very similar to a normal skin pimple.
These glands normally produce oil to protect the nipple and areola. When one gets blocked, a small bump forms and can release white, pimple-like material, exactly like you reported.
This is not a sign of breast cancer. Cancer does not behave like this, does not release white pus, and does not appear suddenly like a small pimple that drains when squeezed.
Your recent breast ultrasound was normal, and that further confirms that there is nothing concerning deeper inside the breast.
Another important point is that your period is due in a few days. Breast tenderness and small bumps around the areola often become more noticeable in the premenstrual phase due to hormonal changes. This is very common and resolves on its own after periods begin.
Next Steps
1. Continue using mupirocin ointment twice a day for 3 to 5 days.
2. Do not squeeze the bump again, because squeezing can make it refill or cause irritation.
3. Keep the area clean and dry.
4. Use warm compress for 5 minutes once or twice daily to help it drain naturally.
5. Wear a soft, non-tight bra until tenderness eases.
Health Tips
When to seek review:
If the bump becomes large, painful, very red, spreads beyond the areola, or if you develop fever. Based on your picture, this is not the case.