hope someone can help me- i have a lump in the centre of my chest between my breats. its hard and round, and doesn;t move. it started hurting tonight. i am breastfeeding and have a 2 month old baby. the lump arrived when i was 2 months preg and i was told not to worry at the time, but its got bigger- you can see it under my skin. is it just the breastfeeding?