Unknown Coolant Leak

quick question, I have a 2012 mustang 3.7 liter.

coolant leak, it started as a small leak, but now its leaking every time i start the car and run it for a while. It doesn't leak when the car is off and parked however. Thinking it may be the thermostat housing unit, or maybe water pump, hose maybe?? But does anyone have any suggestions as to what it could be? Thank you!!
 

Do you know where it is leaking at? It could be any number of places, although there should be some evidence somewhere.
 
I had a similar issue the heater hose under the intake manifold. (In the valley) was dripping at the elbow then just sitting in the valley and baking