Hi I Developed A Rash A Couple Days Ago -

Hi
I developed a rash a couple days ago - just on my arms and legs, and possibly the back of my scalp.
I wasn't worried about it, but the night before last my vertebrae at the back of my neck really hurt - I had trouble sleeping; like a really sore neck. That seems to have subsided, but now I have sore hands, sore muscles and my hands and feet are slightly swollen. The rash has receded, somewhat, and mostly just affects my hands and feet now. It was never really itchy, but it did itch a little.
I haven't changed detergents, or eaten anything new, or used any new moisturizer, or anything.
Any thoughts?