Woke up today, shower has only warm water, low pressure - all the other faucets fine

Hello friends,


So, this morning our shower stall (no bath) has barely warm water and low pressure out of nowhere. If I turn it to cold, the pressure goes up to normal and the water is freezing. Our other shower/bath combo in the hall bath is fine, and the sinks are all fine. 50 Gallon water heater that we own, in a condo with 6 units. We are on the second floor out of 4 floors.

Any ideas? The place is 6 years old. Thanks!