Unexplained allergies
Yesterday I had an allergic reaction on my body. I don't know whether the air or the food, was the cause of that. I had* never had this kind of allergic reaction before, that was the first time. Fortunately, I feel much better today.
* You use the past perfect "I had + (never) + verb..." to talk about a complete or uncompleted action in the past BEFORE another action in the past. In your case, "I had never had this kind of allergy..." happened before "yesterday", when you had the allergy.
Good sentence.
