Dog Has What Appears To Be Hives. Bumps That Suddenly Appeared In Size From Peas To Silver Dollars On Face, Back, Sides And Legs. Nothing In The Environment Seems To Have Changed. She Is 18 Months, Had The Bumps For About 3 Hours Now?

You might call your vet or emergency clinic for some advice once they are able to get all the details to at least make her more comfortable safely and what to watch for and discuss the whole thing and the possibility that she may be running a temperature and when you would go in.
That she is restless can indicate she is extremely uncomfortable, they can handle a lot more than we can without seeming to show reaction or discomfort or pain so when they do we know it is really an issue usually and well beyond when we would end up at the doctor or emergency room.  A phone call to check on her and what you might be able to do for her safely can only help.
Hives can also be caused by extreme stress. You actually have to have been exposed to something at least once somehow to have an allergic reaction, it's a wacky immune response. You can suddenly have a reaction to something after years of exposure (even daily) to something.
Hope she's feeling better soon.