2 year olds nipple swollen and purple

My 2 year old (26 months) has one swollen breast and a nipple that’s a bit purple. It’s been like that on an off for the last week. Sometimes it’s normal but mostly it’s not.

My partner thinks it’s likely growth hormones which will subside on its own. I have a family history of breast cancer so I’m pretty jumpy about it.

Should I take her to the doctor of leave it?