My mother's breasts itch? Also warm/hot?

Hi, my mother has been complaining about itching from the inside of her breasts for about a week. Her nipple does not itch, just the inside of her breasts. She feels as though her left breast itches more. They started itching at about the same time, and have been itching since. They're both also warm/hot in the inside, but if she touches her breasts they feel normal temperature.

She said she thinks her left breast is a bit bigger, but in my opinion I think she's just over thinking things now since she might be scared it's something like cancer.

Does this seem like something possibly dangerous? I.e. cancer? Or could it be something like allergies?

Should she just visit her dr (better safe than sorry)?

By the way, she's 40.

Thanks for any feedback!