Chicken that is limping.

I found one of my chickens alone and sitting down. She moved off as I approached but was visibly limping. I've checked her leg but cant see anything and she doesn't pull or react to my touch. Ive separated her. She'
s eating and drinking. Any ideas on what yo do next?

Hi Everyone, just a little update on the hen... shes been to the vet (I know madness) and the vet identified an abscess at the top of her leg in her feathers, look kinda green blue in colour. She's on antibiotics now.

Find out about egg withdrawl with the drug, if with other hens it might be useful to separate her if all the eggs are the same colour.