I'd also be intersted in finding out what this is, as it is happening to me also! However, I feel teh most cramping and pain between toe #2 and toe #3 (it's toe #3 that is "growing" apart from toe #2). If I curl
under, it will immediately result in this cramping/pain.
Yesterday, when I was trying to take a nap, I experienced a most excruciating cramp in that toe/area and I could literally SEE toe #3 angling toward toe #4.