Regardless of the Why's , you really need to get your pet into a vet immediately to be seen.
The symptoms you are describing could be due to several different reasons, but most of them are serious and require prompt veterinary intervention!
Toxemia due to either an infectious disease process ( tick borne disease, bacterial infection, ingestion of a toxin), etc, can cause the signs that your pet is displaying. Bacterial or viral meningitis can also be deadly and cause the same symptoms in dogs. Add to that any possibility of Distemper or Rabies virus in your pet if vaccinations have not been kept current.
Bloodwork must be done as soon as possible to try and identify what organs in your pet's body may be failing. In addition, screening test for tickborne disease and other blood parasites may need to done to try and rule out their possibility.
Supportive therapy consisting of antibiotics, antiinflammatories, antiseizure medications, and fluid therapy should be implemented ASAP.
Please do not wait any longer, call your vet or the nearest local emergency vet center NOW and get your dog in to be seen!!
Please update me on your pet's progress!!!
Best Wishes to You and Your Pet! Dr. Jodi L. Smith
Thank you for relaying the VERY important information that she has already seen a few vets!! Your original question was brief and made no allusion to any treatment she may have received.
The fact that routine bloodwork is normal is reassuring to the extent that it means the kidney and liver have not sustained damage.
Nonetheless, more diagnostics need to be done... routine bloodwork alone will not give you the answers you seek!
I would highly recommend that she have a CSF tap or cerebrospinal fluid tap done to assess for any evidence of inflammatory, infectious, or cancerous cells in her spinal fluid.
In addition to ROUTINE bloodwork, it is important that rickettsial titers and screening for toxoplasmosis be done in your pet. Leptospirosis titers should also be checked!
Skull and spinal radiographs should be taken to assess for any possibility of a mass effect within the skull or spinal column. Any suspicious lesions would suggest that advanced diagnostics like a MRI be done to specifiy the lesion.
I would be sure that one of the antibiotics that she is on is Doxycycline in case tick borne disease is a factor for her.
Anti nausea medication may need to be given via injection to calm her stomach down. She may be vomiting more due to a nausea/seasick effect than a toxic effect.
I know you have already seen 2 doctors, but your pet sounds like it may require the services of a board certified internal medicine and / or neurologist. You should consider having your pet referred to a specialty practice or state veterinary school for a third opinion and workup.
I do believe your pet is very sick, and I regret that you are having such a hard time finding answers.