Is it normal that after a shower

I will have an after shower dump usually

It is probably the shampoo or conditioner. It makes your head itch because you either, A, didn't wash it out well enough or, B, need a milder type. Ask your doctor what kind of hair you have, and which shampoo is right for you.

You might not be washing all of the shampoo out.

try a milder shampoo from a different brand and use cooler water maybe

Poor shampoo/conditioner, over washing your hair, washing hair with hot water, change of the season/weather, dehydration...I try to change the heat when I wash my hair.

Your hair itches or your head? Like scalp itching?

Mine is too..and so does my skin often.
It's probably your scalp, not your hair.
So you're probably showering too hot/long or using a bad or agressive shampoo/soap.
Hot water, like it removes oils from dirty dishes, also removes the natural oils from your skin and can irritate it.
But it's not easy giving up those nice long hot showers >:(