If only vomiting in the middle of the night, this is often due to acid reflux. In order to prevent this, 2 things can be tried, either simultaneous (best) or one or the other.
Pepcid can be given before bed at a dose of 0.25mg per pound of body weight. Do not repeat more than once every 12 hours, and you really shouldn't need it more than just before bed.
The other thing which should help immensely is splitting feedings into 3 times a day, with the last meal given immediately before bedtime, to keep his stomach fuller. The meal next morning shouldn't then be on a completely empty stomach. Sometimes a higher protein diet can help with this as well.
Hope your dog is better soon, and let me know if I can help further.