Don't worry, it is benign

Gus runs out of the family room to get a toy and I hear a "thud". Then a few moments later, I hear a moan. As I run into the next room he is lying on the ground, dazed looking. I pick him up and he tries to cry but can't. I sit down with him and he is ghostly white. A bead of sweat has formed on his upperlip, and his skin is ice cold. He is lethargic and there is no color left in his little body. Within 10 or 20 minutes he is back to normal.

From http://www.merckmanuals.com/home/sec23/ch269/ch269g.html

A breath-holding spell is an episode in which the child stops breathing and loses consciousness for a short period immediately after a frightening or emotionally upsetting event or a painful experience.

• Breath-holding spells usually are triggered by physically painful or emotionally upsetting events..

Breath-holding spells occur in 5% of otherwise healthy children. They usually begin in the first year of life and peak at age 2. They disappear by age 4 in 50% of children and by age 8 in about 83% of children. Breath-holding spells can take one of two forms.

The pallid form typically follows a painful experience, such as falling and banging the head or being suddenly startled. The brain sends out a signal (via the vagus nerve) that severely slows the heart rate, causing loss of consciousness. Thus, in this form, the loss of consciousness and stoppage of breathing (which are both temporary) result from a nerve response to being startled that leads to slowing of the heart.

The child stops breathing, rapidly loses consciousness, and becomes pale and limp. A seizure and incontinence may occur. The heart typically beats very slowly during a spell. After the spell, the heart speeds up again, breathing restarts, and consciousness returns without any treatment. 

This is the only second time Gus had a pallid breath holding spell. The first time, he was 4 months old. A pale, limp, non-breathing, bradycardic baby doesn't seem normal, so I called 911. This time, Gus didn't completely lose consciousness, and I was knowledgeable about the "non-life threatening" nature of pallid breath holding spells. Looking at my deathly pale, diaphoretic little boy, I tried not to panic. I can't wait till he out grows this!