sinusitis
"I was prescribed Augmentin for a severe sinus infection. After about 3 days of taking it, I developed this weird skin rash first on the knuckles of both of my ring fingers, then noticed I had the same spots on my knees in the same place on both knees. This spread to both of my elbows also and creeped me out a little so I just stopped taking the medicine altogether. It did seem to take the sinus infection away, but I make sure to tell my doctors I'm allergic to it now just in case I have a more severe reaction in the future. This rash just looked like red dots, no burning or itching either... Pretty strange."