Via PM and various chats, I know that a number of people in this thread are trying a few different approaches to try and resolve this issue. Hopefully, one of the approaches that has been discussed (either here, or in private) will have some success.
On my end, I'm going to look into land titles registry in Stevie's region. I'm familiar with the systems in Canada, but not the US, so it may take me a few days. At any rate, I'm going to lookup ownership info on Stevie's address. This is public record information. It is likely that I'll either be able to get the information about his parents (if they are owners) or his landlord (if he is a tenant).
One way or another, I'm hopeful that whatever contact I net from the search above, will be able to provide me with an update on Stevie's whereabouts and health. I know he mentioned that he has just moved, but that shouldn't be a problem, as land title registry usually maintains decades of history.
If the address is owned by a parent, there may even be some work/employment phone numbers for them recorded in connection with a mortgage (if there is one) registered against title. Even if not, we can probably figure out a phone number based on their names. And of course, if it's a landlord renting the premises, they may be able to help me get in touch with someone other than Stevie who would be able to fill us in as to his health and status.
One way or another, we've got a lot of collective brainpower here, and a lot of knowledge that we can communally throw at the task of figuring out where Stevie is, and how he's doing health-wise / life-wise.
We just need to stay persistent. Hopefully all is well with Stevie, and this is just the result of some little life-hiccup.