Noticed this morning that one of my breasts has a swollen lump, near the top, on the outer side. Never noticed it before so decided to keep an eye on it. Checked now and it's still there and can feel a definite swelling, in a lump shape 
Any clues what this may be or may have caused it?
Note I have never had children, so never breastfed. Am currently TTC but definitely not pregnant.
And I will be phoning to see a doctor in the morning! Just hoping someone can put my mind at rest! 