I am premenstrual, and I know breasts can become lumpy in this period of time, but I have a lump in my left breast which I noticed around a week ago, and I have been experiencing pain in this area for 2 weeks now. I am also very stressed as I have exams very soon, and wonder if this could possibly be Da Costa's syndrome? I'm really worried, but know if I see my GP, he will say to wait until my period comes. Please could you give me some advice. Thank you.