I have a 5 1/2 yr old pomapoo. He has always spit up water from time to time after drinking too quickly, but has begun doing this more often recently, even when he has not had a drink of water for some time. It is not normal vomiting, as the water seems to come up involuntarily. Sometimes, it is just clear water, other times it looks foamy or mucousy.

Tonight, he was lying down sleeping beside me, when suddenly he just jumped up spitting up water (seemed to just come up, he wasn't hacking or anything before hand)- he was shaking his head violently from side to side, snorting, and licking his nose repeatedly. (Couldn't tell if water came out of his nose as well?) Then doing the whole "reverse sneezing" thing.

He also has developed an occasional cough and it seems like his nose is running (can't tell if it's his nose running, or if it's just wet from water possibly coming out of it?).

Aside from that, he is eating and drinking normally, very playful, and doesn't seem to be acting any differently than usual. Any ideas what could be wrong? Allergies maybe? I plan on taking him to the vet early next week, when the office is open, but in the meantime, is there anything I can do to help him? What could possibly be wrong with him?

Also, he does have seizures on occasion, roughly one every 2-3 months. The vet said he couldn't determine the cause, and that it's best not to have him on medication if it's not frequent, as the meds could do more harm than good. The seizures he has are odd, though- not the typical flailing limb seizure- he just tenses up, waves from side to side, eyes go wide... he just kind of shakes and vibrates, breathes really heavily, whines... sometimes vomits up foamy mucous when he is having a seizure, but never looses control of his bladder or bowels. I had a bichon who had seizures, and they were very different from the ones that my pomapoo has. Not sure if this is related at all, but figured I'd include it if it is possibly pertinent to what else is going on with him.

Thanks for any insight you may have!

Id take him to the vet - he may have an esophageal issue.

What causes that? And what kind of treatment would he possibly need?

If an animal vomits regularly, it needs veterinary attention. A veterinarian will try to determine if the animal is truly vomiting or if it is regurgitating. Is your dog eating and drinking like normal?
The most common esophageal problem in cats and dogs is megaesophagus this actually translated to "big esopagus" So basically what happends here is the esphagus has lost the ability to contract and it can't properly move the food or water down to the stomach.
But there are so many other possibilities, that you really should get him looked at by a professional.
They will usually do an exray to determin what exactly is going on. A lot of times when they are having these types of issues, it relates to acid reflux, which is really easily treated, as long as it hasn't done any long term damage.

Yes he is eating and drinking as usual--- it seems more like regurgitation than vomiting, as it always just comes up effortlessly- no heaving or gagging, just spits up at random, even when he's just lying around. I'll be taking him to the vet in a few days to have him checked and will follow up with the results in case anyone else is having the problem with their dog. Thanks!