Instinct (Extinct Book 2) by Ike Hamill

This book is the sequel to Extinct.

Surviving the end of the world wasn’t enough. Driving away an alien invasion wasn’t enough. Faced with certain death, Robby’s group is on the move once more. They’re headed west, hoping to find other people who have escaped the apocalypse. To live, they’ll have to uncover ancient memories. They’ll have to use every Instinct.