DD just said her nipple has been sore since yesterday. I had a look and she has a hard lump behind it. I've done a search here and there are lots of threads about this happening to girls and it being breast buds but it's mainly 9-10 year olds. DD is 7.5 and really skinny, she even wears some age 5-6 clothes. She looks far too young for the start of puberty. What else could it be? Or can breast buds really appear that young?