Diana's info is important. My poor hen Betty used to do that - I had posted similar photos. She ended up getting bad internal infections. For awhile antibiotics and anti-inflammatories worked and she would go back to seeming well and happy. Then they didn't work anymore and I had a hysterectomy done on her but she was too infected at that point and didn't make it - the vet said rotting eggs were inside her - she must have felt so terrifically sick, poor Betty. I hadn't done the surgery as a first point of attack hoping she wouldn't have to endure it and yet ultimately did it because she and her roo friend were so bonded I wanted to save her for him and vice versa. She probably would have been fine if I had done the surgery early on (at which point her exact problem was not really unknown, but was speculated). Poor Betty went through a lot - too much really. All this said, it is also possible, as Diana notes, that this is a passing thing. Your hen may well be fine for a long time to come.
JJ
