What Cause Breathing Difficulty And Nasal Congestion?

So, I go to the doctor walk in for breathing difficulties, lots of mucus in my air passageway and had trouble breathing while sleeping. They took a chest x ray, gave me a shot steroid in the butt area and a ventilator. The chest x ray came out ok and the ventilator help my passageway and breathing, i still get a lot of mucus and the shot steroid cause the muscle tissue to disappear, i have a dent in my butt area. Can you explain why this would happen with a steroid shot. I have not gone back or called the doctor walk in as of yet. The black and blue mark that was there has gone away, but the dent in butt is still there. It sounds funny but it is true and my wife is joking about it,, but i still am very curious why this has happen ann will the muscle tissue come or return mike