Why Does My Left Breast Hurt When I M Very Hungry, And How Can I Differentiate Growing Pains From A Serious Issue?

Nothing concerning just curious really. Why does my left breast hurt when I get really hungry? Not pregnant or anything. Whilst I m at it... How can you tell the difference between growing pains in breasts and an actual problem causing pain? Get them all the time but I m 18 now and I don t think I have much more growing in me