Wow, I don't think I can answer all those, but I'll give a shot with a few.
The Whole Dog Journal had an article in the Dec 2006 issue about eating poop. There are others things to try. SEP, stop eating poop, contains different ingredients than the For-Bid. Also could try a bit of Fig Newton with the meal or a tsp of plain pumpkin. They gave other tips, but it's one of those thing where you're just going to have to keep trying.
First off, though, I would consider this: In the meantime, the antibiotics have taken away all her good gut flora. When you take antibiotics, it kills all the bugs. We need the good bugs to help digest our food. So, she probably isn't getting good food absorption, and could be re-eating in an effort to re-supply her with stuff she needs. Go to Target pharmacy dept. and ask for Culturelle. Since she only weighs 7 lbs. I would only give 1/8 - 1/4 at a time at each main meal -twice a day, anyway.
Also, I would try giving her food more often during the day, and before bedtime. Her stomach is so small that she can't hold much food at a time, and that could be the reason for the morning vomiting.
You can also try and improve the digestion of the food she gets by adding an enzyme product. I have read posts on here from some people who recommend Prozyme. This will help to digest the food. The WDJ says that many vets have had good results by adding enzyme powders to dog food to help with pica or coprophagia (stool eating).
If Prozyme doesn't help, then try Seacure. It's fermented fish. Fermented means the amino acids will be pre-digested, so the amino acids will be readily available for the dog's body to absorb.
This isn't an exhuastive list to try, but a good place to start. I would not do the meat tenderizer - it has a ton of salt, and espeically for a dog your size, that could be wayyyy too much. While waiting to get these products, you could try 1/2 tsp. of strongly brewed plain chamomile tea twice daily with the meal. Don't have a clue how that helps, but it's one of the things they list to try. The other things makes more sense to me, but you never know.
I don't know about the whining. If you are feeding her twice a day, again, it might be helpful to feed more meals thruout the day. This way you can find out if she's crying because she is hungry. She might be crying because her stomach hurts - and that's possible with all the antibiotics. So, maybe with the probiotics it will help to heal her gut.
She needs to come off the antibiotics. A muzzle does not keep a dog from eating - but it might slow her down enough that you can stop her from eating her poop. This seems a necessary step in order to get off the antibiotics.
The price of spay seems steep to me. I don't remember what mine costs, but I think it was probably around $300. It's not whether the humane society is any good or not. It all depends on the vet. Not who runs the place. So, there could be an excellent vet at the humane place, or just someone out the door of vet school. You don't *know* that person.
I think working on a smaller dog would be more difficult, so I would want someone more experienced with this surgery. I would not search around and get a new vet that operates without you getting used to the vet and seeing how much trust you can put in that person. But, yes, it does seem a bit high.
I would do a search and see if they are alternative vets around, and see what your options are. If she was not around any other dogs, and no chance of getting pregnant, then I would wait to do the surgery. I'm thinking that because of all the antibiotics may have depressed her immune system some, and I wouldn't want to do a major surgery when my dog wasn't in top shape, if I could help it. That's if she's always indoors, no other male dogs around, etc. If this is the case, then that would give you some time to see if you like any other vets and get recommendations from others, etc.
But, that's going to put you in an ackward position with your other vet. If you like her, then why don't you talk to her and be honest and upfront about the issue. Say something like: I like you as my vet, and I'm glad you will treat all my different animals. But, I have to be honest, I just don't have the funds for Coco's surgery. I've already spent so much on the shots and puppy visits. I'm not sure what to do. Could you give me a break on the spay since I bring multiple animals here. I
really don't want to go to anyone else, but I am in a bind with the finances and not sure what to do.
If she says she can't change the prices, then tell her you understand, but will have to think about what to do next. You need to leave this conversation in a good place since you still take your parrots there. If you do leave, then make sure she understands it's because you simply couldn't afford it and not beacuse you don't trust her or like her.
But, again, I wouldn't just price shop and go just anywhere else. Yes, it's common surgery - but it's your tiny 7 lb. baby. You do want to go to someone who has had a number of years of experience and does multiple spays a week.