What Causes Rash Along With Small Patch On Arm?

I am a 55 year old woman and developed a rash on my body that is not very itchy. There is a small patch on my arm as well. I don t feel sick and I don t have a fever. I went to see a walk in clinic and the doc said it looked like petechiae. I had a recent complete blood test that was normal. He did not seem worried. Should I be? Should I get further testing?