Awesome. Thanks for the additional information. I really appreciate it.
It definitely sounds as if he's got a little acid reflux going on that is triggering that vomiting. It's actually very common for a dog with acid reflux to have some vomiting in the evenings, especially if they don't eat close to bedtime.
You can read about it here: http://www.vetinfo.com/dog-acid-reflux-symptoms.html
When it comes to treating acid reflux, I've found the use of Omeprazole (Prilosec) seems to work a bit better than the Pepcid (Famotidine) . I had a pitbull that had reflux and both Pepcid and Tagmet never seemed to help, but the Prilosec really did the trick.
You can find more information here:
I also gave him a meal at bedtime (which is something you might want to consider doing) and that helped as did adding boiled white rice to his diet. If your boy is one of those who won't just scarf down food immediately, you could leave a small bit of food in his crate (if he uses a crate at night) or just in the room where he sleeps so that he could eat when he's starting to feel the acid building up.
If he is one of those dogs who will eat as soon as food is given to him, then you could try using an automatic feeder like these: http://www.amazon.com/Best-Sellers-Pet-Supplies-Dog-Automatic-Feeders/zgbs/pet-supplies/2975352011 where you can set a timer for a time (such as 10pm) to give him a little bite to eat while you sleep.
I hope this helps.