shroom
Hi Quetar. Histamines are produced in "mast cells" which get activated when they come across IgE antibody isotypes attached to antigen. There are also other immunogens {chemicals} which can signal their activation as well. Mast cells contain tiny little "sacs" of amines and other acid like chemicals which when released, act like weapons against foreign substances and invaders. They can also cause damage to "self cells" and tissue. There are also chemicals which causes tiny veins to open up-{vasodilation}. This helps other immune-cells to get to the site of infection.
Obviously this can cause inflammation and irritation to various sites [pain, itchness, swelling].
Histamines also regulate hydration, so to prevent the constant release of these things, massive water intake is nessasary for a week or so, until the body is fully hydrated. After this, you should not need as many trips to the bathroom.
As for candida, there are many ways it can effect the release of histamines.
If you have "leaky gut" --which is the case with many hive sufferers, enzyme intake is essential along with high quality fish oils.
The possibitlity of gluten intolorance is very high--so try avoiding it.
Candida can release many antigens at the site, and systemically.
An itchy rectum after bowel movement is a good sign that you have over-growth happening. Shroom