My poor potato face

So, Saturday morning we woke up and the eye lid above Saber's left eye was swollen.  By 9:15 am we took her to the vet.  Got some ointment; thought it was done.  By noon, her other eye lid swelled up.  Called the vet as they were about to close, and they told us to give her benadryl (sp?)  .  We gave her that and the swelling went away.  Cue dinner time, about six or so, Saber comes out of her crate with this face.  Cue emergency vet.  Also, cue belly hives.  A shot later and more benadryl and she is normal. It looks like there was a bug bite on her belly.  Does anyone know what kind of bug bite could elicit such a reaction?