Could Itchy Red Patches With Scaly Skin In My Armpits, Groin, And Base Of Penis Be Dermatitis Or Psoriasis?

Hello, I have this itchy red patches of skin that started in both of my arm pits. After a while i have seen the same one in my groin and now the base of my penis. It is really itchy sometimes. When i skip the shower a day or two, the area is scaly like its shedding skin. I m using dove, lotion and coconut oil when it flares up because it s really itchy. I keep on searching and results that i took into account were dermatitis and psoriasis. I am not familiar with any std or sti s too but the shedding skin took me with the direction of psoriasis. What can it be?