Jessica, it's hard to say without seeing it or a picture, but it sounds like your new plant has dried out. What kind of water has it been getting, and if root bound when taken out of the pot to plant (many are), did you loosen up the rootball to allow roots to begin to establish out into the surrounding soil? It's possible with a tightly rootbound container grown plant to water, only to be moistening the surrounding soil and not the tight rootball itself.

Planting too deep can lead to decline too, the azaleas surface roots can't function deeply planted.

If it has dropped its leaves, looks dried up, you have nothing to lose - lift it out and check the rootball. Let us know what you find.

(Miracle Gro didn't cause the problem, but it didn't help either, you aren't describing a problem with nutrients/fertility. They need little in the way of fertilizer if any at all when grown in soil of average fertility and the correct ph. If you must fertilize, possibly look for HollyTone by Espoma....a better choice.
But again, fertilizer isn't your issue, don't fertilize a stressed-for-other-reasons plant.)