There’s quite a bit of helpful information here regarding allergies
http://news.cnn.com/health/nickel-allergy-info Essentially, you really ought to avoid any food prepared in nickel-based cookware...
As for what to stay away from, the list includes canned sodas, herring, oysters, asparagus, beans, peas, lettuce, mushrooms, both white and red onions, corn, grits, spinach, tomatoes, pears, whole wheat flour, rhubarb, cocoa, chocolate, and even baking powder...
If I may offer a bit of advice, I wouldn't recommend picking up clothes, like jackets or similar items, at flea markets; it's much safer to stick to major retailers. You might also want to swap out those metal buttons for plastic ones, and try to steer clear of cheap costume jewelry altogether. Generally speaking, it's best to only wear titanium, high-quality surgical steel—not the inexpensive stuff you find at a street fair, but the genuine, premium kind—or pure yellow gold.
I've been dealing with this allergy for several years now, and I must say, it can be quite a struggle. I find myself constantly reaching for Claritin or Diphenhydramine whenever a flare-up occurs because the itching is so intense that I end up scratching my skin raw. Over the last year, things have actually worsened, and I seem to react within just a few hours of exposure.
Oh, and one more thing... try to avoid direct sunlight and secondhand smoke, as both can make the reaction much more severe.