I Started Zithromax Day Before Yesterday And Woke Up Yesterday

I started Zithromax day before yesterday and woke up yesterday with a red ring around my neck. I've taken this antibiotic a long time and no problems. Don't know if it's a reaction to the antibiotic or cause I was sick with strep throat. Started clindamycin today and still have a itchy throat inside so I took some Benadryl. Is this a reaction to antibiotics or irritation from being sick? I'm allergic to penicillin sulfa and cipro. Running out of options. Scary