I bought 26 egg laying day old chicks last October. All was well and every chick survived to this point but I have one production red chick that goes nuts every once in a while. I have a 40 ft. by 50 ft. open chicken run for them to scratch and run around in so they have plenty of space to do their thing. About a month ago I noticed one of the pullets run around wildly for about 30 seconds. This evening after I threw them their daily treat of scratch I witnessed this pullet started to run at full speed along the fence till she got to the end of the run and hit the run fencing at full stride, she got up and started to run along the other way at full stride till she hit the other side of the fencing and stumbled, she got up again and ran at full stride till she hit the other side at full speed again. She then got up and started scratching like nothing ever happened and acted normal. She runs like something is chasing her, it started to make me laugh until she was hitting the fence. What do you think is causing this????