What do you suggest if i have an errection when i think about dressing up /when i dress up, is it a problem"?

Paraphilia: Medically, what you're describing is classified in the category called Paraphilias. In this case, more specifically, a fetishism. Generally speaking, for most people, it isn't a problem unless becomes disabling, psychologically distressing, or causing harm to others. There are many treatment options. More info here: https://mrkmnls.co/2xHt9pT Hope this helps