Thank you for your question. I’m sorry to hear your kitten has not been very well recently. With the symptoms you have described, Feline Calicivirus could certainly be a cause, and it seems your vet is probably thinking the same based on the treatment he has prescribed. The ulcers your kitty has now developed on his tongue will be very painful for him and because of this he won’t feel like eating properly. I would advise revisiting your vet who will be able to draw up an appropriate treatment plan for him. Your kitten will require pain relief and may need supportive treatment such as fluids. Sometimes a feeding tube may need to be placed to ensure he gets adequate nutrition whist the ulceration settles. It seems you are very caring and dedicated owners, so together with your veterinarians’ advice, I am sure you can help your kitten back to recovery quickly.