What Causes Smelly Vaginal Bleeding During Period?

I normally used to have a 6 day period i.e four days bleeding then one day rest and it continues and stops on the 6th day. Later it changed to 4 days bleeding only. Now it's back to the previous trend but I noticed that I could bleed lightly for 2 extra days the extra bleeding smells bad. pls wat could be wrong with me?