Classic allergies occur usually within an hour or two of contact with the trigger. But sometimes people can have delayed reactions that can take days or even weeks to show up.
But if you are having burning and itching, it could either be a reaction to something, or could be an infection (fungal or viral, most likely) -- steroids that work so well for allergies can make it so our immune system isn't able to respond as effectively against infections.
Be sure you talk to your doctor about your symptoms. Oh, and steroids can also increase the intensity of anxiety, so you may want to consider some relaxation techniques or supplements/herbs or meds for anxiety as well.
Chronic Lyme, Bart., Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut dysmotility & non-specific inflammation, Lupus, Osteoporosis, etc.; G-Tube
Meds: Flagyl, Domperidone, Zofran, Claritin, Andrographis & other herbs, homeopathy, supplements, etc.