Hello, thanks for your question today! I am Dr. Drew, and I am a licensed veterinarian. I'll be happy to help you in any way I can.
The situation you are describing is consistent with some type of inflammation or irritation of the bladder lining,
also known as cystitis,
which in some cases may not have an obvious underlying cause such as infection or stones,
I would caution against continued use of Metacam in an elderly cat, as this medicine has been linked to kidney damage and failure with repeated usage.
If x-rays and ultrasound of the bladder have not yet been done, that needs to be the next step, to look for signs of stones, polyps, or tumors.
any of those could explain the signs you are describing.
If no cause can be identified, this may be a case of Idiopathic Cystitis, which may need to be managed with a combination of pain medicine such as Buprenorphine, anti-anxiety medicine such as Amitriptyline, stress-relieving pheromones such as Feliway, and a diet change to a prescription urinary formula.