Wobbley acting chicken

Hello! I just acquired a group of 5 chickens Friday. It's been hot so they've been staying in the chicken run part of the coup the first few nights they've been here. Today (Tuesday) is the first day I let them out of the run and around the yard.

One of the ladies has been hanging back from the rest. She laid about in the Nesting box that's in the run. She eventually followed the rest of the ladies around the yard but would pick a spot to lay down and sleep. I was able to scoop her up and i got her to drink some electrolyte water.

I noticed her vent was looking red and swollen. So she's currently soaking in a warm water bath just incase. Is there anything else I should do ? Should I isolate her from the rest?