Update 2: So what we got was Purina Game Bird Chow Growth and Plumage. Is that okay for my duck? I'm starting to get worried again because I'm afraid it's not the right kind of food for him. It's not like I can do anything about it if it's the wrong thing but I want to know if he'll be okay. My parents have been buying it for him for a while so I dunno anymore. He seemed healthy before while he was eating it but I have no clue.
Also, one or two of you suggested I get another duck, but that's just not possible for us unfortunately. My parents said they are done having pets after the ones we have now. I know it's wrong because ducks are social animals, but there's nothing I can do, I don't really have much say in family matters. I try to spend a lot of time with him, but I doubt that's enough. I feel so bad.
Edit: It's also occurred to me that there's different kinds of growth and plumage feed in that brand. I dunno which one we got, but I'm really hoping that the store owner understood what kind of feed we were looking for as we told him it was an adult Pekin.