It's so hard to say without having seen it in real life, but I think I recognize the symptoms  - at least from how you describe them.

Pure guesswork here!

Is it all over her body or concentrated to a few patches? Are the patches in places exposed to dirt - like around the lines of a rug? Has she been wearing a blanket/rug a lot? Has she been wet a lot (with or without a rug.) At this time of the year, horses tend to be more receptive to skin problems as they are a bit run down with the change of coats and maybe not enough vitamins/minerals to make up for the cold and dark winter season.

(Sometimes we think we have tended to their needs, but it is very hard to really know what each horse is absorbing and if amounts and combinations with other trace minerals are correct.)

I've seen this happen when horses have had superficial scrapes or sores, but also eczema, that has healed and then the scabs or dead skin is coming off in flakes. Sometimes with tufts of old hair attached. There is any number of skin conditions that causes that, though.
The important question here - I believe - is whether the condition is all over the body, or just a few spots.

If it's the latter, I wouldn't worry too much since there is perfectly healthy skin beneath and this is the natural way for the body to dispose of dead patches.
If it is the former, however, you might want to examine the entire body to see if the condition is ongoing with more, unhealed, eczema hiding in the winter coat.
In that case you also may want to call in a vet. Sometimes a (couple of) baths with special ointment will be necessary, as well as clipping the entire horse to get dry air down to its skin.

Also, a thick rug can give the horse "rashes" due to being too stuffy and warm, and how long any one horse can go with a rug unrelieved is very individual.

Not sure if this is of any help, but fingers crossed Star isn't too affected and that it will clear up by itself and some more good grooming. :)

Thank you Kicki  o much. It is just in one place. And underneath, before I washed it, it looked like very dry skin. No inflammation. She had this one spring many years ago.
It could very well be her diet for sure. Here in this part of Canada good quality hay is very hard to come by this time of year.
She gets her F&F everyday, during the winter and her mineral block. 
This the first Spring I have ever seen her coat have no shine to it. It looks dull and not one length and sparce. Clinging to her body.
She has never worn a coat and hates the rain, she has a walk in closer and she heads there if it starts to storm.
I'm concerned it may be a sign her immune system is down. I'm going to call Carl, her vet to see what he thinks as well.
Again thank you. I hope it is eczema!
Ronda

Hi Star and Kicki;  `Just finished reading your posts.  Another thought to consider would be her mineral intake..  You mentioned her salt block.  I learned a few years ago how very little actual minerals were taken in by a horse from licking the salt block.  I ultimately switched to granulated minerals for horses, WOW what a difference for all of my horses.  I only wished I would have known about this many years ago.  You might do some investigating on your own with regard to the minerals.

`Hope this helps

Bud

Thanks very much. That is interesting. After grooming her everyday with her metal scraper, I think that's what they are called, for removing winter hair.
Shes looking much better. Now if she would just stop rolling in the muck we would both be much happier.
Soon I'm hoping it will get warm enough to give her a good spring bath. The water will probably be black. Lol.
You all have a nice day.