Me too!!. I hope he isn’t really sick.
I'd try the shirt rub first. If that isn't enough this may help;
From valanhb ;
You put a dab of vanilla extract under the chins, at the base of their neck (by the spine) and at the base of the tail (again, on the spine not the underside of the tail!) of all of the cats to make them smell the same. Cats recognize each other by scent, so if that kitty smells the same as "me", the he must be a friend. Kitty logic at it's finest. This trick works when introducing cats into the household, and also when one of them has been to the vet and therefore smells different to the others who didn't go.