This can be a very painful condition and is caused by a fungal infection, Candida albicans, commonly known as thrush.
If you are breastfeeding, you may experience thrush. It is extremely painful and affects both breasts at the same time. It may occur following a course of antibiotics. However, it is important to ask your Midwife or Health Visitor to check that your baby is attached well at the breast, as the pain from a poor attachment can be mistaken for thrush.
If you are taking a medicine called warfarin, DO NOT use Miconazole cream. Contact your GP for further advice. If baby has signs of thrush and you do not (and you are breastfeeding), you must get treatment for yourself.