Know how you are feeling but don't panic. We lost one of our cats for he week before he plodded in one morning, we live near fields and I presume thats where he was. He must have ignored us when we walked round the fields calling his name. A couple of years ago we found a cat in our garage, the owners think he must have been there a few days. If you have checked all the obvious places nearby its probably going to be ok. More recently my friend lost her cat for nearly a week and they eventually found her holed up in a nearby barn with a supply of caught rabbits. Anyway best of luck, thinking about you