My one year old outside cat came up today walking very carefully and slowly, though he isn’t stumbling or falling. I brought him inside and offered food and water. He was interested in the food but would not eat, though he did drink some water a few licks at a time. He is lethargic and just wants to sleep, though he will stand and walk to follow me around or if I pick him up and put him on the ground. He is still affectionate, purring, and aware of his surroundings. I’m just at a loss.
It sounds like your cat is not only not eating but is also acting lethargic. These signs together mean that you need to get your pet to a vet to find out what the underlying cause is. For more information about why a cat is not eating and what to do, here is an article on the very topic: https://www.vetbabble.com/cats/food-and-diet-cats/help-cat-wont-eat/
However, even as the article mentions if you have other signs, such as lethargy it is very important to see a vet. While it could be just that your cat is tired or being fed by a neighbor, it could also be something that needs to be addressed straight away such as toxin ingestion, or a number of other conditions.