Good solution for a memory foam allergy

We purchased this Sealy Naturals mattress because I had an allergic reaction to a Stearns&Foster mattress purchased from Macy's a few weeks earlier. The allergy started as a mysterious irritation on my back (an itch and small red spots). It became a painful dry red rash. I eliminated possible causes (medications? pets? a rough seam in the back of a nightgown?). Finally I wondered, "Could it be the new mattress?"