Is the chick's one foot curled up, like a little chick fist ? If so, my guess is that it could be curled toe paralysis brought on by a riboflavin deficiency that normally present between 10 and 16 days. As the chicks grow they'll need less riboflavin, so it should grow out of the problem if they get the riboflavin they need right now. If a chick with curled toe paralysis doesn't get it's riboflavin there can be irreparable damage to their sciatic nerve. I'm not a vet, but just went through a huge search to figure this out for my own 10 day old and then a 12 day old chick.
ttp://
www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/206930.htm
My calculations resulted in me doing the following to get what I believe is the appropriate dose of riboflavin in my 10 day old chick that had curled toe paralysis. The chick completely recovered in 2 days and about 7 days later I gave it a second dose of the same amount.
Take 1 capsule of B2 (a/k/a Riboflavin) that has 100mg of powder inside the capsule.
Open the capsule and dump all the powder onto a plate. Using a straight safety razor chop the powder until there are no lumps. Shape the powder into an rectangle. Cut the rectangle in half, then cut one of the halves in half again, keep cutting one of each successive half in half for 10 cuts total. You'll end up with a teeny pile of B2 about the size of a ball point pen tip. According to my calculations, that should be +/- 100-µg of riboflavin, the recommended dose according to the Merck Vet Manual.
Please note that 100mg is NOT, repeat NOT the same as 100-µg, that first being 1000 times the latter !!!
I used a tiny syringe without the needle, you could also use an eye dropper, and I "scooped" that tiny bit of B2 up with the corner of the razor and put it in the syringe, then mixed with about 0.3cc of water. Then I shook up the mixture and gently opened the chick's little beak, and put the tip of the syringe gently at the back of it's tongue and squirted the B2 laced water down it's throat.
By the next day, the chick was walking much better, two days later running, and by the third day completely better. I did another dose about 7 days later. I had a second chick who had the same symptoms about 2 days later. I did the same again on that chick with the same results.
All chicks are 11 weeks old now and doing fabulous in the "big chicks'" run/coop.
Hope that helps someone's chick !
Good luck.
