Suggest Treatment For A Rash On The Elbow

I had a hepatitis b booster around ten days ago. Within a day or two of the shot, I developed a rash on my inner elbow. it has gotten worse and is very annoying. I have a history of mild eczema in this area of both arms which I have treated with an ointment in the past - although the problem has not occured for many years. What can i do to fix this?