Head back to where the Fisherman is. Now use Waterfall to head up the waterfall to his north. Once you've traversed it, move north along the water. You'll be at a T-intersection. Head east and move onto the little strip of land north of the water. Use your Dowsing MCHN to find the Nugget hidden here.
Now head back onto the water and head back to where the waterfall that you came up is. There's some land to your west. Move onto it and head west along it. Continue until you reach the Black Belt at the end. He's much stronger than the other trainers that you fought in this area, so be ready!
Trainer Battle: Black Belt
Grab the Nugget near the Black Belt, then head onto the water to his west. Drop down the waterfall here. If you move onto the land to your west and follow the path along, you'll reach an entrance to the Abundant Shrine . Feel free to head into it and begin exploring.
If not, continue down the stream until you reach the last part of land you can explore. Move onto it and use your **** Dowsing MCHN to find the hidden Protein . You can now either head back west and enter the Abundant Shrine , jump over the ledge and continue exploring Route 14 or head somewhere else! Your choice.