My cat use to roam around the house with zero problems. Then one day he flipped out didn’t eat or drink for a couple days and will not come out from the upstairs bedroom. We took him to the vet and they found nothing wrong. He is eating and drinking again, using the litter box etc. but he will not leave the upstairs bedroom. We moved his food to the bottom of the stairs to try to get him to come out but that is as far as he will go. Idk what to do and asking for any tips to get my cat to be social and roam again.