I had a full body wax for the first time.i have broken out into very large rashes including on my arms groin and entire buttocks. what should i do?

Time, cold bath: It's much more likely to be from the trauma of having your hair ripped out than a potential allergic reaction to the waxing product. This will likely improve over anywhere from a few hours to a day or so, and a cold-water bath or shower may feel good and relieve some of the redness/pain. Creams/products are unlikely to help a rash of this type.