Embarrasing to ask this?

hi,this is question regarding my older sista,recently she has experienced some sharp pain more like sore on her right nipple,she even went to see nurse but nurse said its might be due to period,she said just have a record of ur monthly cycle cos she said people do have this tenderness before period,my sista is 30yrs she has 2kids.n this has just started recently,yeah it is like a week or few days b4 her period,what can this be help me to help her thanxx