Sulfite allergy symptoms can seem very random - there are lots of sulfites all over the place (air, food, water). Reactions depend on exposure over the previous 48 hours plus your individual sensitivity level. So you could eat the same thing for 3 meals in a row and not react, but if you eat it again the next morning, you may react because your sensitivity level has been reached with the 4th meal. Or you could eat those same things 6 meals in a row, then go out side and get sulfur dioxide fumes from car exhaust and factory emissions, and then get the reaction because the air pollution outside is what triggered things for you. I had unpredictable reactions for years before a very astute doctor figured out the common link for me was sulfites.
A safe thing to try if it is possible you do have a sulfite allergy is to take a Vitamin B12 supplement (at least 1000mcg/day). If you notice your reactions occur less frequently, then it is a good bet that you are allergic to sulfites. Vitamin B12 binds directly to sulfites, rendering them much easier for the body to get rid of so they don't accumulate and cause problems. There is no upper limit for B12 (i.e., no known toxicity issues), so it is safe to take on a daily basis for years.
Also, if you do start having a reaction again, you might want to try taking 1500-5000mcg of Vitamin B12 in addition to your other allergy meds (Benadryl, etc.) and see if your reaction calms down any easier. If you are reacting to sulfites, the B12 is likely to help.
The only test for sulfite allergy is an oral challenge, which would not be safe in your case (since you anaphylax from whatever it is you are reacting to).
Chronic Lyme Disease, Chronic Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, chronic Lymphopenia, etc.; G-Tube; Currently trying to wean off TPN.
Meds: Pulmicort, IV Ceftazidime, Heparin (to flush PICC line), Claritin, Domperidone, Colloidal Silver (used topically), probiotics, Milk Thistle, homeopathy.