Clementine tracked Sam, she tried her best but she couldn't find him because Sam was one of the best when it came to covering up his trail.
Even the best trackers in existence wouldn't be able to find him if he didn't want to be found.
Clementine, unfortunately for her, wasn't exempt from this as she was
There was no other way to do this, she didn't know how long she could keep going but she had not only seen Sam but established that the fragment had somewhat corrupted him.
Clementine regretted falling for his trick because if she hadn't, then Sam wouldn't have come into contact with the very things destroying his mind like some cancerous cell.
It was like a drug that hooked anyone unfortunate to come into contact with them.
Clementine needed rest, she had been away from the military base for a year and wondered how her friend was doing.