My experience with smelly hair is that this happens because the hair is not dried properly. If one leaves a rag wet for a while, it will star to smell. Now imagine that this rag gets a bit dirty, it will smell even more. The same happens with hair if its left damp for too long and especially if one sweats a little it will smell! Never go to bed with your hair wet especially if your hair is thick. If the hair stays wet all night it creates mold , this is one of the main reasons for smelly hair.
Baking soda is the most amazing miracle for smelliy hair. After washing the hair give it a rinse with a cup of water and a teaspoon of baking soda .