Yes, you can still feed. It may hurt! Try and squeeze the pus out to get rid of the infection. The feeding will help get rid of the infection as well, baby's tum will kill off the infection. If you start to feel poorly see your doc, you might need anit biotics. I had this recurrenlty until 6 months. Never took the anti biotics though, it always cleared through a couple of days of horrible painful feeding. Good luck!
I would definitely see the GP - you may have the start of an abscess , especially if you can feel sore lumpy areas within the breast. You CAN continue breastfeeding, though baby may not like the taste, and of course if baby is getting just pus and no milk... may well not be satisfied at the end of a feed on that side.