If it looks infected, you can contact your doctor.
I would get blisters and open sores from pumping. First, find ways to prevent it and to keep them from getting worse. Make sure your horns are the right size for you and that your pump isn't set too strong. I was told no more than 1/4-1/3 of the full power. You can lubricate your nipples to keep them from rubbing too much. To do this you can apply a little olive oil around the base of your nipple before pumping. My LC told me to do this and said it is safe for the baby.
To heal the nipple, I suggest trying a few different things. After pumping you can dip your nipple into a warm solution of salt water. This can help soothe, heal and prevent infection. You can also apply breastmilk and let it air dry. This has remarkable healing powers. Many people find lanolin helps. When it was really bad, I would also add in nipple shells. That are hard plastic shells that allow the nipple to heal by keeping all clothing off of it and allowing for air circulation.
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