Hello, and thanks for your question.

I'm sorry your cat is having this trouble.

While it's possible that he might have ingested a toxic or other non-food substance, causing his present symptoms, as you suspect, it's also possible that he might have chewed on an electrical cord and sustained a burn in/on his mouth or on his tongue. Look for any especially red or sore areas on and around his lips, sides of his mouth (inside and outside) or sores inside his mouth and on his tongue. Also, check for any swollen and/or red areas inside his mouth around teeth and gums, which may indicate a dental problem, and also check inside his cheek areas. Check that nothing is wrapped around the back of his tongue. Cats can also develop tonsillitis, and if his tonsils are swollen, this would cause painful swallowing.

It's important that he eats and drinks, of course, to avoid dehydration and liver problems, so if he's experiencing discomfort swallowing and is uncomfortable using his tongue, it would be a good idea to have him evaluated in person by a vet, as soon as possible, for a definite diagnosis and treatment.

Symptoms to watch for now, in addition to what you've already described, relating to toxic ingestion, are vomiting, diarrhea, difficulty breathing, lethargy, constantly dilated pupils or uneven pupil size, and seizures.