Itchy dry rash on my shoulder, inflamed after shower?

I have these weird blotches of dry skin (that's the best I can describe it) on my left shoulder and it's spreading to my back and my left shoulder. It itches a lot during the day but to look at it, it doesn't look like much, just dry skin, really. The pigment of skin in the area is a little whiter than everywhere else but after I take a shower, especially a warm one, I will look in the mirror and the area is extremely blotchy and red, but only the parts that itch. The red areas are nickel to quarter in size and once my body cools off, the redness goes away, leaving me with dry, itchy skin. I've never had this before. Just within the past 4 or 5 months. Any ideas what this could be? My mom suggested a fungal thing. Thanks in advance for your help.