I did a basic levels on the whole picture.
Open a new blank layer above the picture and set the mode to Color. Keep a finger of whichever hand isn't on the mouse on the Alt key. Pick a small-ish (I used an 8 I think) soft brush with the opacity at 75%. (Sometimes I use less opacity, sometimes more - depends on the color. Dark colors need more opacity.) Select your paint brush and put it in an area of good color and click that Alt key. It turns your paintbrush into a color picker. I started on the brown trousers. Start painting over the discolorations. Every so often hit the Alt key and resample the color as it changes throughout the area. You may have to go over the dark stuff more than once. When you're happy with the color move on to another section That is absolutely all I did to your splotches and I did nothing in the background. I ran it through Noiseware to calm down the blotchiness a bit. With a bit of cloning and cleaning up it'll be as good as new