Finish the Scar and Tank battle in the Bandit Camp during the Day after you talk to jester about visiting Scar in there during the day (The talk about this can only happen at night i think after seeing Tank chasing a bandit in there at night randomly when sneaking in), after that event is done, go to your house to Trigger Jester's appearence, this unlocks the Forest Path location, go there and maybe do some exploring and the Troll Bridge should appear after coming back to the map screen.