Talk to Dermatologist on Skin Issues

I got patchy, dry, itchy, scaly skin. My legs, back, buttocks and sides of waist, abdominal areas get itchy too much. The itchiness leave patches and redness. When it heals it leaves dark brown spots but after that the condition gets worse. So this happens off and on. It's been more than 8 months I've been suffering from it. No doctor diagnosed what's the exact problem. They say diseases like Dermatitis, Tinea Corporis, Psoriasis, Rosea. But nobody is sure.