What Causes Early Bleeding Just After Menstruation?

My normal period is usually at the end of the month.. Last period was on the 25th July to 30 July .. That was fine normal 6 days. Then on the 4th Aug to 8th August started bleeding again.. Not light or anything.. Quite similar to my period.. Is it possible To have my period in Aug that early? And why? it s never happened before.