This might sound like an oogy question, but do you have cats? Does spike like to "nose dive for the tootsie rolls?" My dog does this every time after I catch him sneaking mid-day snacks in the litter box. The clay litter clumps in there throat and they try to hack it up.
It could also be a hair ball - yes, dog's get them sometimes - especially now when they are shedding so much from the heat. (there is a similar post on here somewhere with a very graphic picture!).
If he has water to help wash things down, he should be fine 'til you get home. It freaked me out the first time my dog did this, too and I rushed him to the vet only to pay about $60.00 for her to tell me there is nothing wrong with him.
I think allergies might cause them to do this, too - like getting a tickle in your throat when your sinuses are draining (would explain the snotty nose, too). When my husband took our australian shepherd to Michigan on a business trip, Rocko was doing the same hacking thing the whole time he was there, but as soon as he got home he was fine. I figured he was allergic to Michigan.
Sending good vibes your way,
Jeanne
