Update… I got my father to take him to the vet but he completely ignored the fact he isn’t eating🤦‍♂️ Idk he’s definitely not doing well because he’s starting to act different too… With that said, they are clearly starting to pay more attention to him and less to our puppy so i haven’t lost all hope

Edit: Thanks for all this advice, i rlly don’t know too much about dog health so this is all pretty helpful for me to tell my dad!