A week before i get my period my breast gets sore my period is due in 7 days what can it be ? pregnancy ?

Estrogen: It is most likely due to the spike in estrogen. Natural Progesterone during day 14-26 might help this. Also avoid caffeine as this can aggravate breast tenderness. IF you continue to cycle and your pregnancy test is negative then you aren't.

Sore breasts: It is fairly common for women to have sore breasts a week before expected menses. It is a result of the hormonal response of the breast tissue to your hormones.