Melinda
I ditto Becky completely on this one - you will need to act fast if she has developed placentits - a lot of vets put little or no faith in the SMZ/Regumate/Banamine protocol, but I have saved several foals by jumping on this action.
Personally, the LAST thing I would do is load my mare up and haul her - if the vet won't give you the meds at least ask him/her to come out rather than stress your mare even more than she may presently be from the current situation - adding stress will only release oxytocin hormones which will also encourage her to abort. You should also pay close attention to her size at this point and if she looks like she is gaining immense amounts of weight very quickly you may also be dealing with a hydrops issue - it is important to be there when she foals if this is the case - the huge loss of embryonic fluids can lead to shock - pretty serious stuff.
Looks like foaling season is upon all of us -- we will keep our fingers crossed for a successful foaling year.
Stacy