itching can be caused by a number of factors... each if which is liekly different for each person depending on their circumstance.
Itching can be caused from inflammation of the scalp and the hair minaturising
It can be caused by minoxidil or any one of the topicals you're putting on your head as many dry the skin thanks to the alcoholic penetrating agents utilised in them.
Many minoxidils also contain mild acids such as retin-a or azelaic acid that can cause irritation... but also reduce androgen binding by up to 30-40%.
as far as nizoril is concerned... this is a steroidal synthesis inhibitor and mainly used as an anti inflammatory. When you use this, afterwards it is highly likely to leave the scalp with some form of tingling sensation which may cause you to itch.
The topic itching is almost as tough to answer as how to fight/fix hairloss..... but yes... in the areas of male pattern baldness it will likely itch more than the side and back of your scalp as a general rule IMO