Marie
There is a homeopathic remidy called 'phytolacca' which is ofthen used
for mastitis. Some of the mothers I know who have used this had a white
spot on the nipple which looked like a white head. When this eventually
came out a long whitish/yellow string followed. Which may be what you
saw coming out while pumping. A homeopath would be able to recomend the
correct remedy for you lady.
Trish