I am getting information that your histamin intolerance stems from a traumatic, unhappy experience in your early childhood, when it was spring/summer and pollen was in the air and grass was growing around you. You may be aware of it, or you may have blocked it out. Either way, it continues to influence the way your body responds to histamin. Your distraught emotions and the presence of histamin-containing substances mingled and created specifc cellular memories that keep instructing your body to fight histamin.
What is needed is to clear the continued effect that your childhood experience has on you and the cellular memories that go with it. I hope this gives you some new direction to go by. You may want to look up the information on my website www.ener-chi.com that deals with Sacred Santemony. Click on "NEW." I use specific sounds to clear up these and similar problems. If you resonate with this, you may contact me at firstname.lastname@example.org.