I am sorry your boy is not feeling well.
When a cat is constipated he is not motivated to eat.
Give him one to two ounces of warm, whole milk right away. It is a natural laxative that should bring on BM within two hours.
Get a few jars of chicken baby food with no onion powder. Warm it to bring out the aroma. Most cats will eat it right up.
He can also have tuna in water, canned cat food like fancy feast or his normal food except hold dry food because it causes constipation and dehydration.
If he gets dehydrated give him tuna water drained from the can.
Please let me know how he is doing .
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