i can empathise. i had a few incidents of over-pumping till i pumped out 'strawberry milk'. no choice other than dump the contaminated EBM. i think it was also partly cos my boy bit me when he was teething that the bleeding occurred.
as for a white spot with pus, i had something like that on my aureola (lower side of my left breast) about a month back (which means nine months into breastfeeding). but i believe was nothing more than a pimple. it was painful to the touch. i was worried my boy would burst it while nursing, so i burst it myself first and cleared the pus, cleaned up the area before nursing my boy. it didn't recur thankfully. i am still not quite sure how the 'pimple' got there but i have taken more caution to keep my breasts clean and sweat-free.
in yr case, since it's been 3 weeks, you might want to see a doc to check what it is exactly.