Mono symptoms an facial rash

About three or so weeks ago I came down with an awful flu-like thing, a sore throat worse than I've ever had, it hurt to even swollow my own spit! My neck hurt even just moving it up and down and sideways. About four days later I went to the urgent care as I'm new to my area and don't have a doctor yet.
I told him I was worried I had mono and he had me move my neck, while it hurt, he said if I had mono I wouldn't be able to do that. He thought I had strep, took a test but it came back negitive, he still thought I had it has the nurses screwed up the test anyhow so he put me on amoxacillian 875mg twice a day for 10 days.

I started to feel much better a few days later but my neck still hurt slightly and then my sore throat came back. This past thursday I noticed my left cheek started to feel a little warm and odd, like sandpaper, by the end of the day I had a fine slightly red rash that feels gritty like sandpaper covering my whole face. It itches like crazy, even on my eyelids! It's now moved slowly to my ears and neck and I think it's even starting on my left arm!

I'm worried sick about what it could be, I've tried to avoid itching as much as possible and have a doc appointment this monday, though I don't think I can wait that long. I stopped that the amoxacillian on Friday but am worried as I've still not totally recovered. Also I've been getting very tired and very much believe I have mono.

Any thoughts?