I Think My Granddaughter Is Allergic To Petrolatum. She Has

I think my granddaughter is allergic to petrolatum. She has had a bad trash, tested for rheumatologist and had a biopsy. Nothing shows. Still a bad rash and have been using aquaphor. Her skin is swollen, itchy and stings badly when using the aquaphor. Have seen the doctor numerous times. My question is what could be used other than petrolatum product to help heal. We are starting a second round of prednisone next but the itching on her face swells, becomes very red dries and gets crusty. Ideas?