As Heiferly stated above; allergies are common in both patients with Dysautonomia, as well as in the general population. Though patients with Dysautonomia are usually told to treat their allergies as histamine is a vasodilator.
As for Mast Cell Activation, I've only recently begun to research its connection to Dysautonomia. Unfortunately, there isn't a lot of information available. Though from what I have read, it does seem that anything could trigger a Mast Cell reaction.
Interesting. Thank you very much for your time.
A lot of people with dysauto also have allergies, but then again a lot of people in the general population have allergies so I don't know if any statistically significant correlation has ever been found. Searching Pubmed and Google scholar right now, I don't see any articles about allergies in dysautonomia unless I'm missing something.
I'm not sure if that could possibly point to MCAD/mastocytosis or not. Does anyone know if masto is ever triggered by traditional allergens? I think this is unlikely in your case, because I don't think your symptoms present as hyperadrenergic, but I'll present the information just in case.
MCAD/mastocytosis are thought to be somehow linked to some cases of POTS:
http://hyper.ahajournals.org/cgi/content/full/45/3/385
http://www.tmsforacure.org/mastocytosis.shtml