Why Do I Have More Dandruff Right After Washing My Hair?

I have had a very similar symptoms. If your scalp feels itchy right after washing your hair it could be an indication that you are allergic to one of the shampoo ingredients. Some people, including myself, are allergic to sodium laureth sulfate or sodium lauryl sulfate sometimes dubbed SLS. These detergents make the shampoo foam and are good at removing oily residues but can be harsh to the skin.
SOLUTION: Try using a mild soap (for example 'pears' a transparent soap bar) instead of shampoo and afterwards rinse your hair with a mixture of lukewarm water and cider vinegar. (Don't add too much vinegar. The water should just taste slightly sour.) Alternatively, try to find a shampoo without SLS.  In any case you should also consult a dermatologist.

Well hair loss is normal unless it is excessive. The average person loses 60-80 strands a day if I remember correctly, but if you think it's worse than that then something might be wrong. If you want to get rid of dandruff try a tea tree shampoo with either the conditioner that goes with it or a good thick conditioner. Don't brush or scratch your head too much cause that could also be a factor. See a professional hairdresser or if you really think it's bad enough then see a doctor.

You should go and see your gp or your hair dresser and tell your doctor what your problem is and maybe he/she can help you try head and sholders to smooth your hair then try a softer brush don't use the hard brushes because they pull your hair out.