[InkedMarie]

Generally, you add a little new food to the old (removing some of the old), gradually adding more new, less old. Look at stool. If it’s loose or too soft, add more old.

Am I reading correct that you bought a different food, not SD and he’s no testing that? If yes, just feed him the wet food he is eating. I’ve cold turkey changed foods & it sounds like that’s what you may be doing.