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I am sorry to hear about your cat screaming so much. My name is Rebecca. I am a veterinarian and will do my best to help.
There are many causes of nighttime screaming in older cats. One is hyperthyroidism. When he went to your vet, do you know if he was tested for thyroid function?
High blood pressure, pain, dementia/senility are other causes of screaming. Having his blood pressure checked might be a good idea. A course of pain/anti inflammatory medication such as buprenorphine or prednisolone might be something to try. Melatonin is a safe supplement that can help induce sleeping at night; he could take 3 to 6 mg at bedtime.
When you serve fresh cans, is the food room temperature, but usually an open can is refrigerated? If eating food that is cold does not make him scream and eating room temperature food does, it might be his teeth, or mouth pain, or just personal preference.
Let me know what other questions I can answer.
I hope you were able to see my response; I have not heard back from you! How is your cat doing? Was this helpful and and can I answer any more questions?