Why is my baby toe numb, when my shoes are not at all tight?

Compression. Usually when the 5th toe is numb, it is because something is compressing it. If nothing is, than it could be from sural nerve impingement or s1 from your back. See your local podiatrist or neurologist.
Several things. Though your shoes are not tight you may be rolling your foot and putting pressure on your small toe, or you could have a nerve problem.