What a coincidence! I am also experiencing a rash on my scalp and behind the ears (as well as ear folds). I am also getting those small, red, itchy bumps all over my body, particularly the mid-torso area. I'm experiencing these symptoms all RIGHT NOW!
Anyways, I also looked up psoriasis symptoms and what not, but have you tried looking up symptoms for seborrheic dermatitis? It's very similar to psoriasis and so can be easily mistaken for it. It also gets worst during winter time due to the dry, winter air.
Best thing to do is keep consulting your doctor for a diagnosis and any medication that would help. Right now, I'm currently waiting for my insurance to pull through for an A-okay to see a dermatologist but they are taking an extremely long time... Please keep us updated and I well, as well! Hope everything works out.
"We make a living by what we get. We make a life by what we give." - CARE