HI, I had a fever for 4 days straight and felt so weak, didn't get out of bed. Then I developed a sore throat. I went to the doctor and tested negative for strep and the flu. But after blood work, my white blood count was a little elevated, so i was put on tamiflu and augmentin. I have a horrible cough I can't get rid of with phlegm. Now, I have a rash on my chest and the back of my neck. What would cause this rash?