I'm new to chicken keeping and this is the first problem that has stumped me, hope you can help!
We have three chickens, one of which, Mavis, has been broody (at least, we're assuming it's broodiness, she stays in one of nest boxes unless we lift her out and put in back in the run) for about the past week. We are putting her back in the run 2/3 times a day to make sure she's eating and drinking and shutting the coop door at the same time so she can't go straight back to the nest box. We're leaving her for half an hour or so until she just waits by the coop door for us to open it up, then she's straight back in on to the nest box.
When she is out in the run with the other two, Chokey (don't ask, this is what you get when you let a 3 year old name a chicken), seems to have a bit of a go at Mavis, chasing her round. And yesterday, I noticed that Mavis' comb has had a chunk taken out of it and is all bloody 
Before this, all three got on fine.
Is it just an issue with Mavis being broody, and will it settle down once she's over it? Or do I have a more serious pecking order issue that I need to sort out?