What Causes Itchy Red Bumps On Forehead And Neck Area?

hi, about a month ago I looked like my upper forehead was sunburned and it went away by night then a week or so later it looked like my forehead was sunburned again but this time it also covered my cheeks and a little of my neck. across the forehead was smooth, itchy and light red, but my cheeks and neck were red and blotchy with small welts. this cleared up fairly well, but forehead is still light red and very itchy and dry and peeling in spots. At this same time the sides of my neck were swollen with a slight throbbing on the left side.. Much more swelling on left side. lower Neck at shoulders, felt soft and pliable. Swelling went down partially but still noticeable. what could cause something like this rash and could it be connected to the swelling on neck?