What Causes Itchy Red Bumps On Neck And Chest?

I have an unusual situation regarding rashes. It started suddenly on Saturday afternoon when I noticed an itching and burning on my neck and upper chest. When I checked it it was extremely red and bumpy and even had some hives on my neck. I also noticed a different kind of rash on my arms, small bumps but no blisters. Later I noticed a pin point type of rash on my stomach. I took a couple of benedryl saturday night but woke up Sunday with the same issues. I took a benedryl Sunday night and still woke up with the same rashes. Now the rashes / bumps on my arms have multiplied and now a red blotchy rash is growing on my arms along with the bumps. I still have the red rash around my neck and chest and the pin point type rash on my stomach. I have noticed in the past hour that I now have a red splotchy rash on both legs. My question is should I just continue trying to treat this on my own or seek medical attention