Hello, and welcome.
I'm sorry your kitty seems to have a bad uti.
The recommended dosage of D-mannose is 2g or a level teaspoon, 4 times a day, one hour apart. This should only require one day to resolve the issue. If it is not resolved, you can repeat this on day 2.
You can see more information here:
In cats, the typical dose of amoxicillin ranges from 5 to 12 mg per pound (10 to 25 mg/kg), two or three times a day. Please read more about this medication, here:
Always consult with your vet before giving any medications to your cat.
I hope your furry boy is feeling much better, very soon!
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