i am recovering from the flu and took one dose, 10mL, of the equate brand of Cough DM, Dextromethorphan Polistirex. That was 24 hours ago, and I have had a very painful rash on by back all day. I also had to take anti-diarreal medicine, two doses yesterday. I am feeling better except for the rash on my back. What can I put on my back to relieve the pain?