I'm having pain in left breast and left arm since a few days. Earlier I used to have some acidity related heartburn. But this time it's not like that. It's mostly swollen feeling in the breasts. While I was on my periods last week, so I thought it might be for that. But it's there even after one week has gone. And if I touch, I feel some lumpy feeling with few lumps. But not sure. Can it be serious? And in case of fibrocystic breasts, can it go away on their own? What can be of left untreated?