Swimmers Toe....Have you heard of this?

I am training for my first Sprint TRI and have been having trouble with my swimming.  As soon as get going all my toes on both feet lock up and feel like they are broken.  I am drinking plenty of water and have added gatorade.  Once I get out of the water my feet are fine and don't hurt at all.  My instructor says I could have swimmers toe.  Anyone know how to treat this or heard of such a thing?