I thought I'd post this thread (in the resources section): http://neurotalk.psychcentral.com/thread161714.html

And this study: http://www.ncbi.nlm.nih.gov/pubmed/23494529

I've been looking into histamine issues myself, and have spoken with my GP about it. I get hives regularly, as well as itches that leave red marks on the skin upon scratching (can't recall the medical term for it at the moment). Clearly I now have a histamine problem along with whatever illness has given me SFN, whereas I didn't before. Histamine levels are high and I'm allergic to all sorts of things now. Clearly a GI and full body problem. When this happens my symptoms increase too.

My doctor recommended an anti-histamine, it was benedryl or reactine, can't recall now, throughout the day, but I'm inclined to first try diamine oxydase, and see if it's due to GI/ingested histamine first. Of course, I think my overall histamine levels are high, though I can't be sure. Regardless, histamine is implicated in whatever is going on with my body.