The vet was out this morning to give Dawn her second set of antibiotic shots. She said that, since there's no more swelling, I could stop using the DMSO/furacin (thank goodness, that stuff is nasty), and can stop the bute as well - Dawn'll get one more gram tomorrow a.m. to help her with any soreness from the shots. I'll keep her on probiotics for about the next week to make sure her insides keep functioning normally. The neck is looking better every day - there are still some pretty nasty, crusty areas, and I'm to continue washing those with baby shampoo every day and gently scrubbing with my gloved fingers to remove crusties and then continue applying the Thermazene antibiotic creme.
And, since the swelling's gone and Dawn's feeling good, I can go back to riding her again, keeping the work light to start with. So back into the rotation she goes.
The vet said we'll never be sure what prompted the swelling - it could have been a bacterial infection or a delayed immune system overreaction to the toxins in the stings. As a result, we may need to be careful if Dawn's stung again, as she may now be more sensitive to stings. Just another thing to add to the list of Dawn's medical oddities and list of accidents . . .