What Causes Pain In Breasts During Period?

I miscarried twins in October 2010, they were only 6 and 7 weeks in gestation, but I'd gone to 11 weeks before my body realised what was happening. Since then I have suffered daily with sore/painful breasts. It's very similar to what you would experience before/during your period, but is daily, and tends not to go away with regular painkillers like Paracetamol. When is it my period, the pain increases, so much so that I can't bare to have my breasts touched, and occasionally need to sleep in a soft bra. Please can you advise why I've suddenly developed this pain? We are trying to concieve again, but as yet have been unsuccesful, and I know for a fact I am not pregnant this month.