No one is going to be able to give you sound and reliable advice form a forum. If anything, we would need pictures of the leg, hoof and descriptions. Even then, you are risking the potential of incorrect advice for the certain injury your horse has, causing more harm then good.
When can your vet come out?
As Kristy said, i'd contact a vet, or a farrier vet (yes, they DO exist!) for further information on the limping.
I can't even offer insight, because a "limp" is so broad... there could be a multitude of things wrong from an abcess or bruise to arthritis or navicular... or even a wound on the shoulder. It could literally be anything. Maybe try narrowing down what else is wrong with the horse?
I've seen many different things come from a limping horse.
Chances are that if it is laminitis, she wouldn't be limping on 1 foot. More than 1 fott would be sore and hot to the touch. And if it started very suddenly I'd be skeptical of a disease. My first guess would be a bruise, but without seeing her move it's really hard to offer an opinion. She could be limping for a number of reasons and it might not even be her foot (could be anywhere from her hoof on up to her shoulder) so if you can't get a hold of your regular vet, call a different one. A good vet will answer you right away and make an emergency visit the same day you call if necessary.
When I found Ella limpinmg one morning, all sorts of horrible ideas ran through my head....I know what you're going through. But like Kristy said, the forum is the last place to ask, not just because you could get wrong information, but becayse people can throw out a million ideas at you, making you very scared at every possible idea. Then you'll turn into a nervous wreck....and a nervous wreck can't keep her head on her shoulders just as her horse really needs her.
Contact your vet asap....I have a lot of ideas to offer you, but not knowing enough information, I don't want to take any risks that could hurt your baby even more.
I'm soo sorry....hope you get someone real soon! Keep us posted!
Thankyou for everyones concern. The vet did come out last night and she foundered. She is now on antibiotics and pain medicine. She is doing a little better today and hopefully will continue to show progress in the coming days, weeks and months. Thanks again!! Jen