My period has been wired the past couple days?

My period was a week late. The first day it came on it was not really that much. The 2nd day it was nothing at all. The 3rd day it was back again but it was heavy the 4th day it was the same. The 5th it was lite again. I only have my period for five days. Day 6 it was gone again. Day 7 me and my boyfriend had sex and half way through we had to stop because there was blood. Since then it has stated coming and going just like it did when it was coming on. I don't know if I should go to the doctor or not. This has never happened to me before. I am on day 10 what should I do.