It’s been driving me crazy and I can’t find it on any list. I don’t remember much but the main character was a younger male, I believe with blonde hair. He had returned to his home town unwelcome. I think he was a troubled kid and I believe after his return he was a pizza delivery driver. If I can remember right, I think one of the townspeople were inflected by a worm/parasite/alien creature and began infecting others. I remember one scene where the main infected person was going after the main female character and she was hiding either in the basement or under the floor watching him look for her.  I know it’s not slither but I can’t figure out what it was.