Hello, I'm sorry to hear about your fellow's vomiting. Is he keeping any thing down? Or is he vomiting even water? If he is vomiting water too then any oral medication may not work as he will likely vomit anything you give him.
Tums are less effective for nausea as they simply absorb the acid and then the stomach produces more. A better idea is to give medications to turn off acid production to settle his stomach.To try and settle his stomach you can give either:1) Pepcid-ac (famotidine) at one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours. OR 2) Prilosec (omeprazole) at one half of a 10mg tablet per 10 to 20 pounds of body weight every 24 hours. These will reduce stomach acid and should help settle his stomach. You can use these for several days if need be.
Then I would with-hold food for 25 hours to let his gastrointestinal system rest. Ice cubes to lick, or small amounts of water, or water mixed 50:50 with pedialyte to replace electrolytes is fine.After his 24 hour food fast try a bland diet. A homemade bland diet to try is 50% boiled hamburger (or white, skinless chicken), all fats drained off, and 50% boiled white rice with warm water or low salt beef or chicken broth added to get more fluids in. If he eats this well feed it for several days and then slowly start mixing in his regular diet. It should take about a week to slowly convert him back to his regular diet.
If he continues vomiting, has a tense painful belly or refuses to eat the bland diet or runs a fever (more than 103F rectally) then he should be seen by a veterinarian promptly.
Please let me know if you have any further questions.
Thank you for the detailed answer!