Shingles as you probably know is a viral infection of the skin caused by the varicella virus, which is the same virus that causes chicken pox. Actually, after you are once infected by the varicella virus (as chicken pox) the virus never leaves your body. Instead it hibernates inside nerve cells along the spinal cord; in times of stress or illness
, the virus can reactivate and cause shingles. The typical symptoms of shingles include a red blistering rash on the skin together with burning or pain in the involved area of skin. It is definitely more common to have a shingles outbreak on only one side of the body (and usually in a typically narrow strip of skin, such as just the side of your arm). However, rarely, it can occur on both sides of the skin at the same time.
I would highly recommend that you go see your primary care doctor
about this issue. They can take a look at the rash on your right arm and confirm whether or not this could be shingles. If it is shingles, there are several medications that can be taking to speed up healing and relieve the pain associated with outbreak. See your doctor!