Wait for the drip in the rear to stop and then turn on the tub/shower. Go outside to confirm a drip. If no drip, start with the sink.
Remove access panel to check for leaks. You might have to pull faucet panel as well. Do not cut under belly panels, the water travels along frame, wires ect, from many feet away.
Check the drain and P trap, tighten as needed. Also check the supply lines at the back of the faucet. Check both the tub and the sink for both of the above.
If leak continues, post pics of tub shower area so we can help.
2011 Coachman Freedom Express 295RLDS- Sold
2015 F-250 FX4 SUPER DUTY 6.2L Gas 4WD SuperCab XL 3.73 rear / 158" WB / 8' bed. Factory anti-sway and brake controller