Hi there
After I learnt about the no poo challenge, I decided to combine it with the rice water hair remedy I was already using. Though I’m just wondering, its been more than a month since I started the no poo challenge, and its understandable that my hair is greasy, but why is it especially greasy on certain days?
Hey there,
I also have s similar problem with my hair. The first two months were very tough, but now it is going much better. I guess the problem could be sweating, not washing them properly (i use clay and sometimes i make it too liquid or do not spread it well enough), period, rough sport etc. What you can do is use a home made dry shampoo on the worst days. here you can find a great recipe i myself use very often: http://thenopoomethod.com/no-poo-methods/. There you will also find other methods, because maybe the method you are using is not the best one for your type of hair 
Bests,
Lulu