Can showers cause the itchy's?

Lately, something in the shower is causing Amanda to have an allergic reaction. Not anaphylaxis, because she's not ingesting anything. But a rash all over her body. When she gets out she is red and has welts and hives. I have read the labels and none of them say "may contain peanut or tree nut products". If they did contain peanut traces, would that be disclosed on the list of ingredients? Could the Aveda Rosemary Mint be the problem? Or is it the body wash?

Not sure what is causing this reaction lately.