Droopiness is because of weight of the fluid accumulated in the eye lid. It is usually purely mechanical and recovers completely. A direct injury to muscle elevating the lid is highly unlikely. The lid may turn blue-black as the blood disintegrates and the collection may travel downwards due to gravity. If the collection is large it can move to the other side as well across the forehead if you lie down with face on the other side! Try sleeping with the face to the same side. Wishing you a quick recovery.