It's possible that the processing used in making peanut butter is different today or perhaps the chemicals used in growing peanuts.
She knows she cannot eat several things and takes care of it herself...When an infant she had severe eczema and would rub her arms and legs until they bled to stop the itching. Thats when they had her tested for allergies, although psoriasis and eczema are also genetically caused and some do outgrow it as they age...
3 of my 5 adult children have psoriasis and its nasty to live with, one son got a special light he uses, he's skin gets raw and weeps. He didn't outgrow it and is in his 50's.