To help settle the stomach you can use of the following, but not as a replacement for veterinary examination include
1.Pepcid A.C. (famotidine) comes in 10mg, 20mg, or 40mg tablets.
You can give it every 12 hours. You can give 0.5mg per pound of body weight. So, a 20 pound dog would get 10mg.
2.Prilosec (omeprazole). It comes in 10mg or 20mg tablets.
You can give in every 24 hours. You give 0.5mg per pound of body weight. So, a 20 pound dog would get 10mg
3.Zantac (Ranitidne). It comes in 75mg, 150mg, or 300mg sizes.
You can give it every 8 to 12 hours. You give 0.25 to 1mg per pound of body weight. So, a 20 pound dog would get roughly 1/3 tablet of the 75mg. Even with bigger pets, it is easiest to get the smallest size tablet. Even a 75 pound dog would only need one 75mg tablet.
4.Pepto-Bismol or Kaopectate
You can give it every 8 hours. The average dose is 1ml per pound of body weight, and that is the TOTAL dose for the day.So, if a pet weighs 30 pounds, they would get a total of 30ml a day or 10ml every 8 hours. This is dosing for regular strength Pepto-Bismol. If you use maximum strength liquid, give half as much.
Do not give any stool softeners. It will likely make him worse. It should have been apparent on the x-rays if he was constipated. If not, you don't want to repeat giving that type of drug.
You generally don't want to give any food for at least 8 to 12 hours from the last vomiting episode.
A bland diet can be some boiled boneless skinless chicken and some cooked white rice.
But, this is really not ideal. Based on your description, I strongly recommend getting back in to the vet for better supportive care.
That should include maybe the vet prescribing Cerenia, a once a day antivomiting drug that is very good.
Wish I could do more.
Hope that information helps