Ugh, this can't be happening?

Well, what was it... lavender? I usually don't have any problems with my mares but I have seen them like yours before haha. But um, this is what some people use to calm a stud as well and it blocks the scent and relaxes them. Just put a little scent old by the nostrils. This is also what people use when they are trying to make a spooky horse seem calm when someone is interested in a purchase. I get weird looks when I am smelling a horse's nostril while check the legs and confo before a purchase haha. I don't know if it would help a mare in heat though... It would relax her some at least.