Cat throwing up?

My cat buddy has thrown up three times in the last week in a half. Twice was food and this last time it was white foam. I have a vet appointment scheduled for Tuesday which was the earliest I could get him in. So in the meantime I just want to know your options on what it could be or what I can do til I get him into the vet. He is about 6 years old.  

As long as he is eating and not showing any other symptoms you should be fine waiting. Although I would ask the vet to call me if they have openings before then. If you notice he stops eating, has a swollen/tender abdomen, not using the litter box or bloody vomit it has escalated to an emergency and needs the vet immediately.

Until the vet appointment just make sure he is staying hydrated. If you pinch the skin between his shoulder blades it should return to normal quickly. If it takes longer than a two count you need to get more liquid in him. You can make a homemade pedialyte or buy the unflavored human version and water it down some. You can also make some homemade chicken broth (canned ones can have added spices and high sodium which doesn't help) or offer human meat baby food (no garlic or onion) which has a high water content (or make your own by boiling some chicken and blending the boiled chicken with the stock).

As to what it could be.... blockage would be the emergency situation and lead to other symptoms as he gets more compacted internally. Food allergy or intolerance or IBS that has developed with age or as a reaction to recent food change. Even if you didn't change food if the brand changed formula it can cause problems. Something he found on the ground and ate. Eating too fast for some reason (although doesn't explain foam vomit). Just to think of a few. Tummy problems can have a ton of different causes or be symptoms of other things though so your vet is best to check with and confirm exactly what it is.

Best of luck!