itchy rash after vacation

My friend and I recently returned from a vacation in South Beach, Miami and erupted in an itchy rash primarily on our arms and shoulders. It was also present, yet not as severe, on our legs, knees, and feet. After going to the doctor, we were both prescribed pretnasone. After reading about the drug, I decided not to take it. My friend just finished her prescription.

It is 10 days later and the rash has changed and is now centralized on my elbows, lower arms and hands. There are still residual bumps on the upper arm and shoulder area, but they no longer itch. They new bumps itch terribly. My friend's bumps have also lessened in severity, but after finishing her medication, we are in about the same place.

I have researched all possible causes, and can not figure it out. I have looked extensively at scabies, sea swimmers eruption, rat mites, and bed bug bites. The symptoms and appearance of my rash just doesn't match anything I have found.


-a few appeared on feet and legs in Miami, but over a hundred appeared on arms about three days after we got home
-they are on the outer elbow but not the inner
-the bumps are now on my hands and fingers...but not in the webs
-they are scattered and in some places appear in clusters and rows of 2, 3, and 5
-they started appearing on upper arms and shoulders and over the course of 10 days have moved to lower arms. Upper arms are scarred but no longer itchy.
-heat agitates the itching

What the heck is it and how do I make it stop?