Soft lumps forming under his skin?

It sounds like he's got hives, especially if he's rolling (itching) alot...hives don't generally 'hurt' persay, but they can itch like crazy!

My mom's Arab got them every spring, for several years, and we never treated them, just kept an eye on them, and they were usually gone in 2-3 days. He hasn't gotten them in years, now, so I'm guessing his body finally got accustomed to whatever he was allergic to.

Anahist is an OTC allergy 'med' for horses; you may want to see if you can get a hold of some of this, and see if it doesn't help him; obviously if he still has them in a few days, you may need to get him checked out by a vet, as he may need something stronger to get rid of them.

Knaskedov,
They aren't as big as the pics show, they are only about 2 cm out from his skin. And there arn't as many

He is not rolling a whole heap, just occasionaly more tham normal.

They look a lot bigger than they are because he is in full winter coat right now. 2 cm sounds about right, he had small round ones and larger flat ones (up to 5 cm wide). JT didn't itch at all, all they really did was look bad, but the vet was worried about what was going on on the inside, the things you cannot see.

Mom2pride's story sounds familiar unfortunately, I've been told JT's mom (full Arab as well) has seasonal allergies too...

Okay then. I'll call the vet tomorrow if it hasn't gone down. Is it anything serious?

I checked on him this morning, and the lumps on his shoulder are almost completely gone. The biggest lump on his stomache has over havled its origianal size. Is it still nessesary to call the vet?

I waited a week before the vet saw him, but that was because I already had the appointment scheduled (pre-purchase). After that I waited another 2 before I gave up and got the steroids.
I believe that if they go away by themselves and that is what it sounds like, you don't need the vet.
You do probably want to write the dates down and where he was when it happened, maybe take some pictures. Should it come back, at least you know when and where he had them before.

Cool. Thank you everyone!

I'm still looking into causes and found this today:

The most common allergic reaction that horses experience typically manifests as hives on the skin all over the body. The causative agent of an episode of hives generally goes unknown, but it can be one of a wide variety of things. Among causes of hives are toxic/irritating compounds in a variety of plants, the stings or bites of various insects, and a variety of chemical compounds. In addition, reactions from ingested or inhaled substances to which the animal is sensitive can be a cause of hives, or more severe allergic reactions.

Generally, the development of hives causes no health danger and is of no significance (unless, of course, they are all over a conformation horse the night before the show!). It often is a one-time occurrence and frequently will resolve spontaneously without treatment. On rare occasions, hives will be a leading sign of a more severe allergic reaction that will require immediate medical attention. A horse with hives should be evaluated carefully and have its temperature, heart rate, and respiratory rate determined and sequentially monitored. The respiratory rate and heart rate are particularly important, and if elevated, could indicate a more severe allergic reaction. Veterinary assistance should be sought immediately.

Here is the link to the full article:
The Horse | Allergic Reactions in Horses

Okay, well they have left within 2 days, so no vet was needed thyankfully. Thank you everyone for you're help!

I'm glad that it worked out well. In the future you might try to watch if he comes into contact with something different and the bumps show up again. That might give you an idea of what the allergy is from.