If you are talking about your daughter, she may be beginning puberty. Most girls begin puberty between ages 8 and 13.
The breast having small 'lumps' that are tender are sometimes the first signs of puberty. Sometimes one breast may become bigger than the other. This is usually followed by a growth spurt 1-2 years later.
If the breast is red, really hurts, has discharge or any other symptoms, speak to your doctor. If you think your child is starting puberty, this is a good time to talk to her about the changes that will be coming in the next few years.
I happen to be a thirteen year old girl, who has gone through the beginning of puberty over two years ago. Tenderness was definitely a side effect from puberty for me, but not every girl goes through the same puberty experiences. The lump under the nipple is definitely normal, it's what will grow to be the fat in every breast. As she goes through puberty, that lump will grow and will eventually become the breast.
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