Sometimes, it happens to me, during my menses, that I have blood for four days and then the blood stops for three days. Then on the seventh day the blood returns, but not as intense as previously. Then it turns to a brown color until the twelfth day. I hope you will guide me to what is correct in this matter.
The days that you mentioned, the four and the six day periods, are days of menstruation. You should not pray or fast during those days. It is not allowed for you husband to have sexual intercourse with you during those days. You should make ghusl (full ablution) after the four days and then pray and your husband may have intercourse with you during that period between the four and the six days. Also, there is no prohibition upon your fasting. If that occurs during Ramadhan, it is obligatory upon you to fast. And when you become pure after those six days, you must make ghusl, pray and fast like any other time of purity. Its days are sometimes together and sometimes separated. May Allah guide us all to what pleases Him. May He provide us, you and all the Muslims with understanding and steadfastness in the religion.
Shaikh ibn Baz
 In response to this question, the Shaikh has basically given the Hanbali view of the question. There are some other views, that state that the entire period is that of menstruation, which may carry more weight to them. Allah knows best.