An epi pen being prescribed means there is a true "food allergy", as in anaphylaxis and other nasty symptoms. Most of what people refer to as food allergies is really what should be known as "food hypersensitivities".
There are varying levels of allergies. The Wikipedia entry
on this topic should help.
Breaking a fast of that sort with fruit is usually a good idea, or cooked sweet potatoes or avocado would work...easily digested stuff.