Take on scromboid food poisoning

I went to lunch today at a place I eat at often, sat in the same seat I always do, had the same glass of water with lemon I always drink and ordered a tuna wrap which I often get. I'm there on a business lunch and as I take my first bite into the tuna, I think "this doesn't taste right". I added some extra sauce and chief down the rest of it and had my normal cup of coffee and continued my work lunch.
But all of a sudden, I felt like I got hit in the head by the flu, if the flu was wrapped in the Zika virus and fermented in Malaria juice.
I went from being able to concentrate to feeling dizzy and light headed, and just uncomfortable. I cut my meeting off short and walked back to work, aware that the bright sun was bothering me more than normal. I get to my desk and a buddy walks past and asks me if I'm ok, stating that my eyes are bloodshot and my entire face flushed. I look down and my arms look like they are morphing from fat cute kid Michael Jackson to freaky kiddie touching Michael Jackson. My stomach is red as a lobster, my arms are covered in hives and my entire body is shaky. Within a couple of minutes my arms look like Gorbachev's head and I decide to hoof it to my doctor. I run into the office and run into the bathroom and proceed to shit my brains out, like you are sliding into first and you feel something burst. They shot me up with prednisone and sent me home.
I walked back to work and got a car to go home and rest. The rash sort of spread and got worse and then better and then worse but by 5pm it was almost all gone.
My first thought was that I could be allergic to something but that would an odd thing to figure out at 40, especially when I ate the same food from the same place I go to often.
I did a bit of research and it sounds like there is some kind of scromboid fish food poising from eating rotten and detaining large finned fish like tuna and the symptoms sounded exactly what I went through: flu like, dizziness, face flushed, hives on arms and torso, short term but forceful diarrhea and facial rash.

My life is not very good