nipple lump

im 35 years old and yesterday my left breast just under the nipple was very sore and still is.i have felt a lump and am not sure what i should do next.it is very tender.i have 3 children and havent breast fed for over 6 yrs.i also have my period at the moment and am not sure if it has anything to do with that.usually my breasts are very sore 1 week before my period but this time they werent sore at all.thanks for your time.

[Computer_Voice]

It could be a little mastitis (infection/inflammation) or possibly a cyst, both of which could feel very tender and present as a lump.  As long as you don't have a fever and the skin around it is not especially warm and red, I would give it a week or two and if it doesn't start to shrink, see your doctor to find out what it is.