For the past few days I've noticed that one of my Sebright hens has been limping. I've picked her up and check her over to see if I could feel any breaks, but it seem like anything was wrong. She's still acting normally, eating, foraging, the norm. except she walks with a limp. The only thing drastic that we have done is replaced the dirt in their run with sand. Could it be hurting her feet? I looked at her bottoms and there are not cuts or bits of sand stuck between her toes. I thought she might've sprained something, though I was hoping it would have healed by now. Any thoughts or suggestions?