Panacur is great; have used it for the snakes as well as Budo. I noticed changes within the day. Budo always ate the most on days when he'd had his Panacur. I hope it works well for your babies, too!
I do not remember what I gave Budo for coccidia, but it was not Sulfamenthoxazole. Tell me what you think of it.
Have you tried babyfood? When Budo's having a bad day in terms of eating, I can usually get him to take some butternut squash babyfood from a syringe. You can also get turkey and chicken babyfood if you're at all worried about their protein. Just make sure it's Gerber or another brand that doesn't add any artificial flavoring, colors, or preservatives. Horn worms are also great for getting their feeding response going, and to get a bit of fat on their bones.