My cat was neutered three days ago and he was acting fine, just a bit weak for the past days. Today, I removed his cone and he was acting normal for the first 5 hours, but now he’s scared and anxious. He’s panting with his tongue sticking out, something he does when he’s scared, and he tucks his tail between his legs when he walks, sits down, or lies down. He even hissed a bit at me, which HE NEVER DOES. How do I help him calm down?