From what I understand, cats who have escaped don't usually go very
far. He could be hiding under a shrub, in a garage or under a porch
nearby, and may not respond to you calls because he is petrified.

IDK how far you are from your mom, or if she is physically able, but
I'd suggest going door to door in your neighborhood with flyers. If
you make face contact people will be more likely to remember you and
call you if they see him.

Another thought is to rent or borrow a live trap and put it on the
porch. Wire it so it stays open and put the food bowl near it. Move
the bowl a little each day until he is eating in the trap (which is
still wired open). Skip a day and do not feed him, then set the trap
and put the stinkiest food you can find inside. With any luck you will
catch him. I would suggest that, right after trapping, taking him to
your local vet.

Also, please contact the local shelters and make them aware of the
missing cat. Check and post on craigslist too.

A note--you will need to re-introduce him to the household, slowly. He
will smell different and be like a "new" cat to any resident cats.

Keep the faith.

Rene