Many runners lose their big toenails, too. Were your hiking shoes/boots tight? In any case, the toe that had the black nail looks good. There's normal nail growing underneath. I couldn't open the picture of the green one, but green does sound like a fungal infection. I had a few green nails one time after wearing acrylic nails for a long time. All I had to do was put some topical stuff on it (don't remember what it was) and not wear acrylic nails or nail polish until the green color went away.

I would definitely see a podiatrist about the green toenail. You don't want the green stuff spreading to your other toenails. Keep your feet clean and dry. Change socks often or wear sandals. Wash the toe with the green nail last. Those were the instructions my podiatrist gave me when I had toenail fungus.