Cooking daikon and smell
Do you recall how you cooked it? I just peel it, cut it into rounds and simmer them for bit. I use plain water if using it in Japanese style soups, or a stronger soy sauce flavored liquid if serving it on its own (or with mushrooms). I also add it to Chinese style beef stews. I've never noticed a strong odor.
Radishes are relatives to the cabbage family. There are enzymes that cause a reaction and the production of a mustard oil which is what gives the radish it's pungency. The enzyme is in highest concentration in the skin. Like cabbage radishes have sulphur compounds which I assume is what you are smelling. Soaking in water may help to reduce these compounds. Chopping will increase them and acidifying is known to increase them as well.