Newly allergy “free”

For context, I developed a severe shellfish allergy to shrimp specifically while I was in the military. This has definitely affected my life since and have had severe anxiety surrounding this since I have had a few severe reactions resulting in ER visits. I recently did bloodwork testing for all shellfish/seafood allergens, and the results are negative for all. Had this happened to anybody else? They said a food challenge would be the next best plan of attack but I am just struggling wrapping my head around how this allergy disappeared since separating from the military. Would moving across the country to a different location be a cause for the allergy to go away?