I have paint over unsanded drywall compound. What is the best way to fix it?
1 - Sand down the spot.

2 - Prime the spot.

3 - Paint the spot with a fine brush. (Brush strokes make it easier to blend the paint with the surrounding walls)

(After drying the paint should look like the surrounding wall, if the paint looks lighter add a second coat)

As for your painter, you probably should have told him you wanted a smooth wall. Painters usually just wipe the wall down before painting, they don't sand the walls unless asked.