Thank you for your patience. As you can probably appreciate, there are quite a number of things that could be going on here with Killian to cause this type of symptom. This could well be that Killian does have a gastrointestinal upset and that he is dry retching (attempting to vomit, but nothing is coming up). The other option here is that Killian is actually coughing/choking as a result of either something stuck in his throat, or even an infectious issue like canine infectious cough (aka kennel cough). Hopefully your boy is up to date with his vaccinations, since if he isn't, then kennel cough is more likely here. If Killian seems to be in distress with this, or if he seems to have any breathing issues whatsoever, then you need to get him seen straight away.
For now, please try and encourage Killian to drink plenty of water. If you are convinced this is more him trying to vomit, than him coughing/choking, then with hold his food for now, and try him with some bland food in 6 - 7 hours. For this cooked boneless, skinless chicken breast and boiled white rice is perfect. If he is refusing to drink, then the worry here is that Killian could quickly become dehydrated. If this is the case, then (as above), do get him seen today if you can.
Please also keep a close eye on his mucus membranes, capillary refill time and respiratory rate as follows:
Mucus membranes - flip his lip and look at the color of his gums. They should maintain a nice salmon pink color. Get him to the emergency Vet if they appear white or very pale pink, or if they are a dark deep red color.
Capillary Refill time - this measures blood perfusion and test this by putting your thumb on his gum to apply pressure. After you release your thumb you will see the gum blanch. Capillary refill time is the amount of time it takes (in seconds) for the gum to return to a healthy pink color from the blanched white color. If 2 seconds or less don't worry - if it is taking significantly more time, again - off to the emergency Vet.
Respiratory Rate - if he is continuously panting throughout the night, this is a sign of shock and or pain and a signal for a trip to the emergency Vet.
Best of luck with your boy. Again, if you are convinced that he is definitely trying to vomit, rather than just coughing, then you could also try some pepcid. The typical dose for this type of situation is 0.25mg per pound of body weight up to twice daily. You can read more about the use of Pepcid in dogs online here: http://www.petplace.com/drug-library/famotidine-pepcid/page1.aspx
I hope all of the above makes sense? If you have more questions or if I can help in any other way, please do not hesitate to ask! If you would like to accept my answer, please press RATE OUR CONVERSATION (I am not compensated in any other way). Bonuses are always welcome. Thanks! I hope to work with you again soon!
PS: If you have additional questions after you rate the question, you are welcome to request me for additional conversations if I am on-line or by beginning your question "Dr. E..." or "Pet-doc..." and others will leave the questions for me.