I am sorry to hear about George’s misadventures in eating things. Sounds like he is quite a handful.
At this point, you have several options but the best option is to remove the screw. Especially if it was made of or coated with zinc as this can cause toxicity and make him very ill and he may experience GI irritation or perforation as a result of the screw moving through the intestines if it has a pointed tip.
If you want to know if the screw is indeed in his stomach, you can take him in and have a radiograph taken. If it is not there, then great but if it is then your options will be to make him vomit or remove the screw via endoscopy or surgery. I would recommend endoscopy or surgery in the event of the screw having a pointed tip as the risks of making him vomit include damage to the esophagus or it getting stuck on the way up.
If you do not want to take him in you can make him vomit at home by giving him hydrogen peroxide. I recommend giving him a little bit of food first as this is the best way to help the screw come up and may help pad the sharp end. He can have a tablespoon of hydrogen peroxide orally and this should make him vomit within about 10 minutes. If he does not vomit, you will have to either take him in to the vet for an injection or see if the screw passes.
If you elect to see if the screw passes, I recommend adding a source of fiber to his diet such as canned pumpkin or Metamucil until the screw passes. If you elect this route, I recommend sifting through the stool to make sure the screw passes. If you do not see it in the feces in the next 2-3 days, then he should be taken to his vet for evaluation.
Does this help with your question about George?