If the bump has always been there, it's probably nothing to worry about. The fact that it's become larger and more painful during your period reflects the fact that your breasts retain fluid during that time of the month, and the pain could simply be a reflection of that. However, it could also signal the start of an infection; so I'd suggest you keep your eye on it, and if the pain and increased size don't subside in the next week or so, you might want to see a doctor to find out what's going on. Also, when you do see your gynecologist, be sure to mention it to him/her, and get it checked – even if it's gone back to normal.
Your boyfriend sucking on your nipple might irritate it, but I doubt he's injuring you; you'll know if he is, because it'll hurt! Take care - PJH
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