just wondering if your a first time horse owner?....if so..or not..i'd be on the phone with my vet....first off a 3 year old mare is way to young to be in foal ( still growing her self) ....i would go to the local farm store and pick up ivermactin gold (sp) x 2...worm her now and then again in 2 weeks (we call it shocking ) have you checked her teeth? horses at that age loose teeth (they look rotten) call you vet to have them pulled....is she out on grass? and what are your feeding her?(hay, grains, minruals ect), untill the vet comes to see her try soaking her feed a few minutes before feeding her, also try adding a cup of corn oil in to her feed, that will also help.
246 what you decribes is epm, very devistating to a horse