I was hoping to get a little more information from you, but I didn't want you to wait any longer for an answer.
It's possible that the little balls you're seeing when your kitty throws up, could be undigested food, especially if this happens right after or shortly after eating. He may be eating too fast and this would be 'regurgitation', not vomiting. The balls could also be food mixed with fur (like a hairball) or just a hairball. If he self-grooms every day, he may be swallowing a lot of fur; he may be grooming his brother, also. You can give him some hairball remedy like Petromalt or Laxatone, according to the directions on the box; these are found in pet supply stores. This will help the fur move through his system better.
He also may be nibbling on a plant or flowers or some other non-food item, which is causing him to be sick.
If you've noticed that he's having trouble pooping or his stool is coming out in small, dry, hard balls,and might be constipated, he may not be drinking enough and may be dehydrated, especially if he eats only dry food. High quality canned food is best for cats, although they can have small amounts of grain-free quality dry food for 'grazing,' as cats love to do.
You also might, just for the moment, give him 1/4 of a 10mg. Pepcid AC tablet, to help calm his stomach and his nausea. The generic name is ***** ***** pharmacies, supermarkets, Walmart, etc. carries them. You can hide the pill in a small 'meatball' of canned cat food or put it in a tablespoon of plain jarred baby food chicken containing NO onion or garlic products. Beechnut Stage 1 Chicken is a good one.
A cat drinking fountain is usually successful, as cats love to drink from a moving water source.
It would be a good idea to have your kitty seen by a vet, asap, to get a diagnosis and treatment, if needed.
I hope all will be well with your furry boys!
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