Your toddler suddenly does not want to wash his hair anymore?
As soon as you put water on his head, he starts shouting? So you cannot achieve the shampoo stage. If you can, the rinse one is another nightmare?
Some toddlers go through “no water in the eyes” or “no water in the ears” phase.
To avoid this I have discovered the bath hats. They prevent water to get into your baby eyes or ears when you are washing his hair. You can find different kind of bath hats.
I chose the crown style one and told my kids are the King/Queen of the bathroom. They love it.
Give a try! Good luck!