I took DD age 5 to GP last week. She's had a sore right nipple since well before Christmas. The nipple went dark first, but has since become a bit paler again, and more filled out. The GP said there is a small lump, like her breast is developing, which could be due to early/precocious puberty or something else, and is referring DD to the local hospital for further investigation. Does anyone have any experience of this in a 5 year old?
I've scared myself by Googling and seen info about tumours causing breast development, and hormone injections for early puberty, and would love some info from people who have been through the assessment/referral process & can tell me what to expect. A lot of the info online relates to older children - 7/8/9 year olds.
Also, does anyone know of any very simple books or websites about the very early stages of puberty that I could use with DD just to reassure her that breasts changing happens to other children too, if she asks? I hope everything might go back to normal by itself without ever needing to get as far as needing a book (till at least 8-9yrs old!), but would love recommendations that I can be ready to buy/show her online straight away if she asks or is upset.
Her left nipple has started to be a bit sore today too 
Thank you in advance for any advice you can offer.