Benson is very ill.
Vomiting over this duration could indicate a foreign body ingestion, pancreatitis, severe infection to name a few considerations.
You can't wait this out any longer.
He is going to deteriorate further.
The panting very likely suggests bad nausea or abdominal pain. There is just no way to appropriately or effectively treat him with over-the-counter remedies.
I do truly believe he should get to an ER vet today for supportive medication, maybe some fluid therapy, and basic testing. Testing that might be suggested includes:
1. Basic blood test
2. Abdominal x-rays
3. A simple in-house test (if they have it) called a snap cPL to check for pancreatitis. Pancreatitis is far worse than just a upset stomach (gastritis). A pet cannot hold anything down and they really need to get IV fluid support.
Also, with no known dietary indiscretion, that increass are concern for other causes like foreign body ingestion or he stuck something.
Hope that information helps