Allergic reaction?

On Monday night I had some cheesecake which had pecans on it then yesterday I had some more because I thought I was just having an eczema break out but it got so much worse last night and today. My face is now covered with a rash (no hives) and is extremely itchy and painful. It’s swelling a little, my eyes are itchy and I have a terrible headache too. Can I just take some Benadryl and see if that helps or should I go to the doctors? My office is already closed so I can’t call and ask them I’d have to either go to the walk in clinic or to the hospital.