What Causes Severe Itching And Open Sores On My Buttocks?

Hello I have psoriasis and eczema, I haven't had any sexually contact n two weeks. Last Sunday I experienced itching in the top crack of my buttocks I started scratching and received open sores. now I know that when I get eczema the area starts itching and I start to scratch it and a open sore appears. I recently went to my gynecologist and she said it did not look like herpes, more so like a sore from scratching but still perform a culture swiped to have whatever I have tested. Is it possible for me to have eczema there. I have scars from eczema being on my buttocks that look like the same thing in the upper crack of my butt. It is a constant itch in the upper crack of my buttocks.