Some women get a bacterial breast infection called mastitis. If you are having severe pain, fever, or there is a red lump or streak on your breast, call your health practitioner. You many need antibiotics; however, your milk won't make your baby sick, and it is fine (and actually helpful to your body) to keep nursing during a breast infection.
Education, perseverance, and trust in yourself and the beauty of using your body for what it was intended for, will help ensure that you get off to a good breastfeeding start. Good luck, and enjoy your baby!