Spotting before my periods are due !?

Hi, for The last seven or eight months I have been spotting approx 2-4 days before my full period starts ,, not sure why this has suddenly started happening... Usually my first day of my real period is the worst i get severe pain for the day then after jus bloating and slight discomfort. Not sure if this spotting is normal? Does anyone kno why this could potentially be happening?