I would go along with the lab work recommended including thyroid, let the vet diagnosis her.
Or find another vet, however, it is not unusual to suggest bloodwork, some vets would like it done once a year.
And what’s wrong with medication that has been prescribed by a veterinarian that has examined the dog, that’s intended to make the dog more comfortable?
The symptoms you describe could be any one of a number of things including allergies.
Regarding the food, again, I would see what the vet recommends. Adding supplements and vitamins seem unnecessary for a pup that young, plus they might upset her stomach more.
I would allow the vet to take further diagnostic tests, get the dog diagnosed, then you can go over your treatment options.
In the meantime I might presoak her kibble and start giving her the reglan as prescribed.
Also, if she hasn’t been spayed, she will be going into heat soon.
