There really are not any safe over the counter meds for this in cats. Now if it was a dog that would be different but cats are highly sensitive to medications so its just not safe to do with them.
You can try bringing the cat in a steamy bathroom to help with the breathing or run a vaporizer in the room with the cat.
You can use a warm compress on the eyes and rinse them with sterile saline or mild boric acid eyewash drops.
But for meds to help with this you need vet prescriptions.
Try warming his food to make it smell more aromatic to help attract him to eating it.
Hope this helps you!
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