Emergency:Please Help!

Patient: Hi my name is Bintou and 11 days ago i had black henna applied on both of my forearms and after 10 days of having it both my forearms are itchy,they have these tiny bumps on them and it isnswollen. I need help on how to treat it. Im really scared that my forearms will get these ugly scars that will last forever. I think it maybe an allergic reaction. Please help me.

Symptoms: Itchy,Swollen,Bunps