The plant is stressed, wet roots and no iron. Rhododendrons like azaleas need acidic soil with irons.

Root rot.

Thank you for responding. How can I make the soil more acidic? I've heard of coffee grounds. And if it is root rot can you tell by the photo if I planted too deep?

Also I was watering with a cup just at the roots but last week I started using the hose and spraying the whole area. I have since found out that you shouldn't wet the leaves. Maybe this caused a fungus?

I would take a leaf to your local nursery. Azaleas and Rhododendrons like to have moist versus sopping wet roots which means you dig a trench to plant them adding lots of organic material to the soil, such as 1/3 dirt, 1/3 peat moss, 1/3 compost and then the plant is placed in a mound above the soil line - especially in clay soil. The organic material forms the base.

To make the soil acidic, you would use composted material which makes the soil more acidic, such as pine needles and pecan hulls. Avoid bark mulch as that pulls iron out of the soil. You can also use chelated iron supplements to feed your plants and to help with the soil. Once established azaleas, blueberry's and rhododendrons will go to town. Yes blueberrys are in the same family.