If your child has had red bumps all over their body for 2 days that itch, it is possible that they are experiencing an allergic reaction. Giving them Benadryl may help reduce the redness and itching. It is normal for the bumps to remain visible for a longer period of time than the itching. If the redness is decreasing, the bumps are no longer itchy, and they are becoming less red, it may be best to wait for the reaction to pass without applying anything else to the skin. If the bumps persist after 10 days, it would be wise to consult a doctor.