I was in the middle of editing my question when you answered. I added some more details as to my history.
Additionally, I found some information on wikipedia about sulfa drugs: "It is important to make a distinction between sulfa drugs and other sulfur-containing drugs and additives, such as sulfates and sulfites, which are chemically unrelated to the sulfonamide group, and do not cause the same hypersensitivity reactions seen in the sulfonamides."
http://en.wikipedia.org/wiki/Sulfa_drug
So, should I be concerned about metabi*sulfite* when it is supposedly unrelated to sulfonamides?