Limping on 1 leg

Hello everyone!! First - the good news: I found the first egg in our coop today!! My 8 chickens are now 5 months old and this was my very first egg ever!! I am so excited and proud for whichever chicken it was!! And I have all of you to thank with all your help in getting us this far!!

Now the issue.... one of my babies is limping on her right leg. She is obviously favoring it and when she's on her roost she tries not to stand on it. This has been going on for maybe a week. I was afraid it might be bumble foot, but I took her in, gave her a pedicure, and found absolutely nothing wrong with her foot. Nothing seems to be wrong with her at all. I was wondering if it could be something as simple as straining a muscle or something? Please let me know if you have any thoughts. Thank you!!