Have Cat Questions? Ask a Cat Vet Online.
This could be a simple case of reflux. You should see the vet tomorrow to find out for sure. If this is the case, your vet can prescribe an antacid that will help a great deal.
Until then, you can keep using a dose of hairball remedy right before meals. This coats the throat and helps with acid build up.
You will also want to feed the cat several small meals a day and see if it helps. Jarred baby food works well and is mild enough to soothe the stomach. Try to stick to chicken/rice or another bland food with no garlic or onions.
Your vet might want to prescribe tagamet to help with the reflux.
Let me know if you still have questions.
Has he ruled out an intestinal obstruction caused by ingestion of hair?
This would be the next place that I would look.
I think that the scope is a great idea and it will give you a lot of insight as to what is going on.
You sound like a great pet owner! I wish more people were like you!