Lather and rotate the soap through the piercing once you have all the crusties off. Let it soak for about a minute and then thouroughly rinse. Wear clean clothing and change your bedsheets. If your bra is bothering you, try wearing an athletic bra. Barbells should be a little longer than the piercing to accomodate any swelling and to facilitate cleaning.
Most people agree that it hurts a lot.
However, it's only for a second. In rare cases an infection can travel into the breast and cause a deep infection. If this is not treated immediately it can result in removal of the breast. However, it should be noted that people also get serious infections from papercuts.