I just read the story of Isaiah from start to finish and want to say that you may have helped him more than you know just by letting him see that someone did care for him. I wish I had read this whole thing sooner because I would have at least offered you an idea that has worked for me lots of times.....not every time, but more than I can count. To rescue a very scared stray who needs help right away, a trap has worked really well. I get them on loan from my local animal shelter/humane society. They are basically a long cage in which you set the smelliest food you can find at the far end. They are spring loaded; when a dog goes in, he must go all the way to the far end where the food is. When he steps in that area, the open end of the cage where he went in falls shut. It does not hurt them because the dog is in the deeper end, by the food. However it will scare them! 2 thing are very important--when you get the cage you must be prepared to sit somewhere nearby for hours & hours watching, because people will steal them! Also you want to remove the cage & dog as soon as he is trapped & not leave him in that vulnerable situation. You might also need help moving him because the cage & dog can be very heavy. But I have caught dogs this way who were very smart & wary; it just takes a lot of your time & patience. I sometimes bring a pillow to sit on & water for myself. Can you ask your shelter if they have such traps & go look at them, on the chance you might see Isaiah again? If you do see him again, you might want to get a trap quickly. Or, if you're totally convinced you'll never see this sweet dog again, maybe this info. can be of some help to you with some other stray in the future. (It has worked for me with cats too, though not quite as well as with dogs.) Sorry this message is so long, and so late! I'm sure everyone reading your story feels like I do, that you are a good & caring person for trying as hard as you have to help Isaiah.
C J