I have been diagnosed with Mast Cell Activation Syndrome.

One of the 1st signed was severe itch with water contact, Aquagenic Puritus ( no sign of hives) but is very closely linked to Aquagenic urticaria. I also am triggered by change in Temperature and barometric changes...There is a FB Group on both conditions. The FB Group on AP discovered that Beta Alanine, a common pre workout supplement KILLS THE ITCH. I have been taking for 5ish years and could not live without. I suggest you find the FB group and search Beta Alanine and see if anyone there has used it with success. Please also look on the NHI's Website and search Aquagenic Puritus, Beta Alanine is list as a option and there is a reference to a paper by two Stanford Pediatric Dermatologists.

As for Mast Cell Activation, AP or AU are very common, so are GI issues. I have attached a medical guide written by some of the Top MCAS Doctors in the world, special note to Dr L Afrin.

I have also attached a document with a link to very helpful resources for MCAS.

Last I heard, (do not know if currently true) Mayo does not treat MCAS, I do not know why, but this is a reoccurring theme in the medical world, especially since COVID has trigger MCAS in so many people. Finding a MCAS knowledgeable Doctor is a real challenge. If you do, you may have to wait 6 months or longer.

I started working with a local Immunologist, shared this guide and we worked through the appropriate testing and began treatment. Most of my symptoms were GI and Skin. I am now feeling great. Most of what I take, besides H1 and H2 Antihistamines is supplements. I found a doctor who really understands supplement and maybe also look into genetic issues, like MTFHR Mutation...

A low histamine diet is also a big help. I added low Carb in Dec 21 and it has been a game changer for me, but I also need to lose some weight, win-win.

There are also several FB Pages on Mast Cell Issues.

Good Luck,
Could not attach this file, so I have pasted it...

Some of the Best Websites with science based, easy to understand information on Mast Cell Issues

The Mast Cell Disease Society https://tmsforacure.org/
is a non-profit organization dedicated to providing multi-faceted support to patients, families and medical professionals in our community and to leading the advancement of knowledge and research in mast cell diseases through education, advocacy and collaboration.

MAST ATTACK https://www.mastattack.org/
SCIENTIST LIVING WITH SYSTEMIC MASTOCYTOSIS. LIFE’S A BLAST.
EDUCATING PEOPLE ABOUT LIFE WITH MAST CELL DISORDERS
Supporting materials for explaining mast cell disease to non-health care professionals
https://rarediseases.info.nih.gov/diseases/6987/mastocytosis
https://www.aaaai.org/conditions-treatments/related-conditions/systemic-mastocytosis
Mast Cells and Autism - The Autism Community in Action (TACA)
Great Info here for anyone with Mast Cell issues. Though geared toward kids with Autism, there is a very useful and simple guide to symptoms, testing, supplements and medications at this link!
https://tacanow.org/family-resources/mast-cell-activation-syndrome-and-autism/?fbclid=IwAR3VHGxDZ4uSS44C6eSft9eS0tI44nA5zxLaoJo_L7cZIF1ltUzaGnY8CEo
Mast Cell PSA https://mastcellpsa.com/15-things-you-need-to-know
We are not sure who the author is on this site, but the information is solid and written in a way that informs and clarifies information/misinformation. They describe themselves as “random-stranger-who-just-observes-mast-cell-patients-often “

Canadian Based: The Hoffman Centre for Integrative and Functional Medicine is a private medical centre that specializes in assessing and treating complex and treatment-resistant health concerns that have not been adequately resolved through previous attempts at resolution.
They had a few very informative pages on their website
https://hoffmancentre.com/mast-cell-activation-syndrome-and-excipients/
https://hoffmancentre.com/mast-cell-activation-syndrome-histamine-immune-system-runs-rampant/
Swiss Interest Group Histamine Intolerance (SIGHI)
Histamine Elimination Diet and Food List
https://www.histaminintoleranz.ch/downloads/SIGHI-Leaflet_HistamineEliminationDiet.pdf
https://www.mastzellaktivierung.info/downloads/foodlist/21_FoodList_EN_alphabetic_withCateg.pdf