Have had an unknown allergy for years, help me figure this out?

[Genevieve25]

I was just hospitalized yesterday 4/11/2016 with an allergic reaction and went into anaphylactic. Here is my history and what I think has sparked the reaction.

2006: Had strawberry yogurt with a cinnamon roll, allergic reaction, broke out in hives with indigestion problems 20 minutes later
2013: Had a milkshake and donut from Krispy Kreme
2016: Had Jamba Juice's Mega Mango and a sip of their PB Chocolate love with a whey protein boost shot, indigestion problems and broke out in hives an hour later, hospitalized with problems breathing.

There has been a number of times in between, but nothing I can really remember. I've also had these items 6 months after I had an outbreak and had no reaction whats-so-ever.

So here is some more history. I have had allergy tests done in 2007 with nothing conclusive. I was tested negative for lactose intolerance in 2014.

I have no peanut allergy becuase I eat peanuts at least three times a week.

Maybe it is the protein? Maybe it's a combination of foods? Regardless, this is so stressful because outbreaks only happen once every two years. It doesn't happen enough to be on high alert, but scary enough to be highly concerned.

Please help if you can.