I also use cat lax because the ingredients are only fish oil. Like my cat did,he has multiple problems that can be resolved with lots of work. Her last day she had trouble breathing and very constipated.. she was in a lot of pain.. Try using a different vet. Or even better,an internal medacine doctor. I would not put him down. Throwing up liquid, even if there's fur in it is not a good sign.I am using a product called Cat Lax. It is supposedly only for vets but I got it at chewy. My cat has been lucky to get smaller portions pretty much when he wants them while I have been home for the pandemic. He gets a full 3 oz can at my waking up. Either a full or half at around 2, and either a full or half at 5 or 6 pm. Then I have an automatic dish release some dry food at 1 am and 3 am. The amount is small just enough to give him a snack.
Maybe someone can tell me should I give the Laxitone (or cat lax) daily? I had though I read on the directions that you should give it daily for 2 weeks and then every other day after that, but I can't find that now. I am concerned that I have been giving it at least every other day and I am still seeing throw ups