Again, I think it is somewhat normal for dogs to vomit from time to time.
I think, though, that we have to differentiate what is normal, and what is not.
The info in the last thread, and even the beginning of this thread, was not, IMO. Here on this thread, you could sense the OP's frustration - days without sleep (or even one night) is not normal in caring for a dog vomiting, no matter how you slice it.
Foods and treats can contain germs, plastic pieces, other foreign objects, poisons, etc. all of which can make dog sick. Then you have the allergy factor.
Other things that can make dogs vomit include their ingesting something they shouldn't - plants, objects from the trash, bones, QTips, pantyhose, yarn, ornament fragments, pins, you name it.
Then you have the medical/surgical issues like blockage, GERD, strangulation, torsion, etc.
I think we, as people, underestimate how sick a dog feels when it vomits. They can't tell us. But based on caring for thousands of people over the years who've vomited and practically begged to have something to make them feel better, it saddens me to hear about a dog being so sick and not knowing why.
I think there have been clues here. My money would be on all the vaccinations and anti-parasitic pills at once, the time before this. (I was thinking about it on the 1st as my dog had his heartworm pill - due for flea and tick pill on the 15th.) And the dog, based on breed, probably has a propensity to vomit. So when he's "sick", that might be what you get, idk - have not had that breed type before. (But as I said, lived with a dog for almost 14 years with colitis, so his GI tract could be set off for days by one wrong thing he ingested. Maybe no vomiting, but lots of diarrhea. German Shepherds can have a propensity toward diarrhea.) I think the vet ruled out a "surgical abdomen" when you visited, meaning an XRay was done to be sure nothing had been ingested and stuck in the GI tract, and/or no twisted innards, and bloodwork, etc. (Right?) Which sort of brings you back to the other things, like foods, allergies, germs, etc.
Again, it is not normal to have bloody diarrhea and that would be a huge red flag that something is very wrong if a dog has it, ever. This can often occur with food poisoning. (And basically, people with food poisoning feel like dying, it's so miserable.)
I would also be very concerned about treats somehow making the dog sick. A lot of discount stores today sell meaty or jerky treats cheaply. I pass them by even though it's tempting. There are just too many unknowns when coming from a country where these things are not regulated. About a decade ago, lots of dogs and cats died from treats from China that had plastic in them. A lot of their treats (pet and human) also contain lead.
I suspect if the dog is better since you've elilminated everything and gone to feeding small amounts, etc. then it probably, this time, was dietary. Now just experimenting with what she can tolerate will lead you to developing a suitable diet for her. I would keep in mind she might not be one who can tolerate a high fiber diet if her esophageal sphincter isn't strong (and allows food and acids back into the esophagus after eating). I think it would be money well spent seeing a GI specialist, but that's up to you. You have a lot of years left with this dog, and based on my experiences with my own dog with colitis, it can be a lifelong thing.