You are more than welcome.It is my pleasure to help such a wonderful person.
He may have an ear infection causing a vestibular issue. It is similar to human motion sickness and makes him feel nauseous and disoriented.
Seizures are unusual in a cat his age. He could be hypoglycemic. Rub a drop of pancake syrup or honey into his gums to raise his blood sugar.
He may have eaten something he shouldn't or have trouble with his liver
What and when did he eat last?
Lets see if he will eat, a cats appetite is the best barometer of his health
Offer canned cat food, tuna anything tasty he will not refuse.
Lets see if he can walk normally or if he is licking any part of his body, holding his leg up or any other signs of pain.
Please let me know what is going on. I will stand by to hear from you.