Willig future hive treatment?

Willig's hives are continuing to spread, only in slow motion. Right now he's getting, once a day, a big scoop of Platinum Performance, a huge heaping scoop of Platinum skin & allergy, a heaping scoop of Riva's Remedies Equi-Derm, and an equal size scoop of flax. In prior years, I have given him this twice a day and with Strongid. His nose and chin also still have that weird "sunburn" looking thing, but as of yesterday I tried quitting the blue antiseptic stuff (I forgot it's name) and am just using the baby butt stuff (desitin?) to see if it makes any difference over the next few days. If it lasts much longer, I'm going to have to finally give up and call the vet.
He has a few small hives scattered over his body, but they are mostly on the left side of his neck and chest (big but flat) where they started, and today, a few more on the right side of his neck - big and flat. Nothing crazy compared to in the past, but each day it seems like there's one more and the neck ones have gotten a bit bigger and flatter.
I actually had an email exchange and then a phone conversation with a representative from Riva's Remedies (http://rivasremedies.com/), where I get the herbal blend (Equi-Derm) of chickweed, plantain, and yellow dock. (I'd put up a link, but they're changing their website this weekend I think, to make it easier to order online.)
The very helpful representative not only knew more than any vet or fellow sufferer that I've talked to, but she had some suggestions:
First - no cob. Horses don't digest corn well, but it also tends to be the most heavily treated with various nasty poisons (my wording), and sometimes it is processed with cow feed, which can have other additives that aren't good for horses. She said there have been a couple of feed recalls from contaminants that the feed stores know about, but there's no requirement that the information about it also gets distributed to the horse/cow owners who bought the feed. So today I took Willig off his 1/4 scoop of cob twice a day and now he'll get 1/2 scoop of oats (instead of 1/4 of each).
Second - no clover! She said frequently the hives are associated with clover. This is weird because that's what I had heard from my vet too, but then the "all alfalfa" diet was the thing that kept them in check last year, after many other failed efforts.
Third - watch what's in the fields and turn-out. And watch what the neighbors treat their fields and turn-outs with. Here's something I've never asked about - whether the timing of them has anything to do with any field treatments that Shannon does for weed and pests. I can't imagine she did one in the dead of winter, but it's probably worth asking, although it seems really unlikely that the one day a week (on average) that I hand graze him would result in hives.
Finally - a lot comes from hind-gut problems, so she suggested I try ulcer remedies and pro-biotics, which is also what one of the fellow boarders suggested. She recommended several that they carry, but I had actually already ordered probiotics, ulcergard, and a free sample to try, and I am anxiously looking at the mail each day. Their remedies are: allerg-ease, equi-cleanse, pro-colon, pro-dygest, and vitamin C. So I will definitely try those next after I go through the ones I'm waiting on.
She thought it was very unusual that we had four horses that have slightly different combinations (I looked at the feed chart today and two (Willig & G) get cob while two (A & M) don't; and two (G & A) go out on the grass rotation while two (Willig & M) don't) out of 21, getting them at different times of year, and not matching any of the "obvious" changes like hay or bedding. I agreed. She also said that they have heard more and more horses are getting them, and that it's getting harder for people to keep them under control with herbs and not having to use prednisone and stuff. Yech.

As an aside, today I jumped Willig over a tiny (two fence) course that I turned into a 3 minute course several times, the last time without stirrups. He wanted to be a little silly about the fences, but I just sat down and rode, and although he was kind of awkward over the little vertical (a little shy of 2'), I think it was because I don't put down the ground line and he didn't know where to take off. That, or he was just being a jerk face. I think he has a sense of humor, because he waits until I put the desitin on his nose, and then waits for me to bend over, and then he likes to jab me with his nose with a sneak attack from behind, and leave a bit white spot from the desitin. Maybe he's always done it, but I think he's saying "If my nose has to smell like a baby's butt, then so do you!"