That's what happens when you mix too many things in a cream without understanding how the ingredients interact. Chemical reaction. Use hydrocortisone on it. Next time add vitamin E oil to you cream and store it in your fridge to balance the chemicals in it.
Clearly a rash, could be an allergic reaction, try taking an antihistamine like Benedryl, it should clear things up. I would say it looks like prickly heat, but considering its winter, lets just say its an allergic reaction