What works best for body rashes.?

I began developing this body rash 5 day ago and I am on my 6th day and the rash is getting worst. If i continuously to scratch my palms or the bottom of my feet it will start to develop huge blisters. I tried using a bar of aveeno soap then after that i use the aveeno lotion to calm the itching down and a few mins later i used one liquid capsule of benadryl every 4hrs. I don't know if I'm not suppose to use the liquid capsules of benadryl or if I'm not suppose to use Aveeno in a form of a bar of soap as oppose to Aveeno in packets containing oatmeal. Its just that when i wake up in the morning i see the rash spreading and getting worst. I don't know if any of the products mentioned above is working for me just wanted to know is there anything else I could try:/