Could my dog have Pug Dog Encephalitis?

I have a one year old pug and three times in the past couple months he's had incidents where he acts like hes drunk. He has trouble balancing and even when he is sitting down he wobbles back and forth. Every time he has puked either before or after becoming wobbly. Its always in the evening and when he wakes up in the morning hes fine. He was checked by a vet the day after it happened the second time and he said he was completely healthy. He said PDE was not likely but cant be ruled out. Is there anyone out there who has experienced PDE and can help me? This dog is my life and I'm terrified he's going to die..