I would insist on them doing tests to rule things out. When my dog got sick they tried everything to diagnose him. He ended up having Myasthenia Gravis. Which a 9 month old (almost 10 month old) dog normally does not get.
I question and research everything now. If your vet doesn't know ask for a referrel to a specialist. It may not have made a difference in Riley's case, but I wish we had gone sooner. It was only one day (we were waiting for biopsies to come back), but I still regret it.
Any tests your vet does they will send to the specialist.
Riley - 11/05/2012-8/30/2013
He will always be in my heart.