Hello, Ruth and welcome back to Just Answer.
I'm sorry to hear that Mouse has been throwing up more than usual, lately.
If you know he was nibbling on houseplants, this could be the reason, and I'm glad you removed them, as some plants can be toxic to cats. However, there are many underlying medical conditions that can cause vomiting and here is more information for you to read:
Especially because Mouse is a 'senior', he's more prone to develop diabetes, hyperthyroidism, liver and kidney issues and symptoms of these and other conditions include vomiting, so it would be advisable to have him evaluated in person by his vet and a routine senior blood panel run, in addition to a thyroid test.
For the moment, you can ask your vet if Mouse can be given 1/4 tablet regular Pepcid AC daily, and this might help settle his stomach. Excess acid or acid reflux causes nausea, and the Pepcid will help with this. Here is additional information about this over the counter medication: Pepcid AC
It's also possible that he has developed allergies to some components in his food. If his food contains corn, wheat, soy, gluten, dairy products, meat by-products, artificial flavors, colors, preservatives, these are common allergens for cats. In addition, some cats become allergic to the protein (meat) source in the food and may need to start on a limited ingredient diet (LID). Several manufacturers make these, with alternative protein and carb sources; Royal Canin and Natural Balance are two that are available either at your vet and/or at your pet supply store. This article written by a veterinarian will be helpful, in its discussion about how we can best feed our cats: http://www.catinfo.org/
When you bring Mouse to the vet for assessment, bring a fresh fecal sample as well, so it can be analyzed for any evidence of intestinal parasites or other abnormalities.
I hope all will be well with Mouse!
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