R.Y.
My daughter as a toddler had some of those symptoms with a stomach bug. Usually the light color poop went with times she was drinking a lot of formula or milk and not eating well. It went away in a few days on it's own. You could give him formula for a few days just because it is easier to digest than cow's milk. Then try milk again slowly when he seems better. As long as he is drinking and still wetting diapers then he may be able to ride it out on his own. Watch for dehydration though, because babies can dehydrate much faster than adults. Check with the doctor if see something that worries you.