Weird fungus/rash/allergic reaction?

So my horse (Sienna) is currently living in a field with five other horses. The property is huge (100+ acres) so she has plenty of room. However, the man who owns it can only get out to it at minimum once a week. This is not an ideal situation, I know. Hopefully she will not be there forever and I am doing the best I can. Please help me out here.
I went to visit her over Midterm break. I almost cried when I saw her. Much of her is hairless. Her legs especially. There are big patches on each of her sides and scattered ones on her neck, butt, and ear/jaw. It's very itchy to her so I don't know how much of the hair loss is due to scratching or the fungus/reaction.
The weirdest thing is what it's secreting/stuck to her? There are these little yellow waxy balls. They seriously look like earwax but they're a bit more firm. I gave her a sponge bath and many of them came off, along with dead skin that was sort of scabby looking and hair. She's been biting herself to itch so I had to be careful because she has some open wounds. I went to the store and bought a fungus spray which I doused her in, and then put a coat of vetrocin all over her.
It's just odd to me that I don't know how fungus could make little waxy balls. They're mostly on the patches on her legs (even behind the hocks, so I'm not sure how that could have rubbed on her if it's something she got into?). However they are definitely on her sides, too. They're all wrapped up in hair/scabby skin and the effect is quite nasty.
I have never seen anything like it. It's definitely NOT rain rot, she's gotten that before and I know what that looks like. Is this some kind of weird reaction to a plant? None of the other horses have it. None of my horse friends (including my equine professor!) had ever sen it before. Please help!

P.s. The pictures are not really a good indicator of what's happening, you can't see the yellow wax stuff in them (well, some by the hocks). But I figured I'd add them anyhow.

Holy crap, CALL THE VET!

To be brutally honest, it looks like mange to me.

You're not going to be able to clear that up yourself. You need the help of a medical professional or that horse is just going to get worse and worse, and may need to be put down after suffering horribly.

Ick ick ick that stuff is NASTY. I would have called the vet immediately but she lives out in the boondocks and apparently he only comes on Wednesdays. The guy who owns the place is going down there today to check on her/spray her some more. I can see if he can find out if there will still be one in the area tomorrow.

It is an allergic reaction to something that bites them or a plant they eat at this time of year. My one horse has it, not anywhere near as bad as your horse, but he gets them every year at the same time of the year. A few of my friends have horses that have mild cases as well. Three years ago, I took him to the vet, as I had been fly spraying him and putting swat on the little hives, vet was convinced it was bugs, I am not so sure, anyways, he gave me an antihistamine, which didn't really work that well and horse was a bit dopey with it. Next two years, I just let it run it's course. Strangely enough, my other horse who is in the same pasture & fed the same things, never gets any. Your horse might need a stronger antihistamine & looks like some of that is infected, I would definitately call the vet, repost when you find out. Maybe your vet has a better reason.

Thank you, that makes me feel a bit better, knowing someone else has seen that before. I am still waiting to hear back from my friend. He is also the one who knows the vet. I'll let you know what happens.

I will going out to ride in a bit here, I will try & get a pic & post when I am work at later on. As I said it's not nearly as bad as your horse's and we have had a few killing frosts, so for whatever reason, they are at the end of their cycle. My hubby just informed the antihistamine did work as the hives stopped oozing after the dosage (it's really his horse), he is sure it's those "swarm" bugs, (don't know the actual name, they swarm in mini clouds and you swallow them or get them in your eyes when you pass through the cloud) as we had a dog suffer from welts EXACTLY like your horse has, with hair loss & swelling on his face. Sorry I had forgotten, this was 15 yrs ago, vet prescribed antihistamine & the dog was uber dopey but it did clear it up. I will say that fly sprays & swat medicated ointment did diddly squat!

I took one look and immediately thought mange.
Worm with an Ivermectine based wormer and wash with a solution of Neem Oil

4 tablespoons of Neem, 2 tablespoons of liquid soap and make up with 3 pints of hot water and wash all over with that.

Ok better screen & pixels on this computer, nope that doesn't look like what Scotty gets, no swelling & it's all clustered. The dogs' face looked like that but swollen and the antihistamine from the vet worked very well. There's few pics of Scotty's but he is at the tail end of it, all the welts are not swollen or weepy, just little scabs everywhere.

Why can't you call the vet?

My horses get similar spots like wearsbear's.They're like bites,crusty bumps...happens Every fall,some horses seem to react more than others.Seem like they are from some kinda bug.There is no surrounding hair loss associated. It does not look like what OP horse has though,that looks more like a fungus infection or maybe like mange as someone suggested it looks pretty extensive,i'd be calling the vet!!!