What Causes Soreness On Arm Near Muscle And Shoulder?

For about 5 days now, i have experienced deep soreness in my right arm as if i tore something in the muscle or shoudler. Then a few spots of what looked likes bites appearred. Now small little poison ivy type rashes are appearing. My arm is very sore and hurts to pick something up. Looked over the shingles info and could that be a possibility? Glenn