Watery poo and wabbly chicken

[Chicken Casey]

Help, I have a couple of chickens that have had watery poo and now one won’t walk. Ive given the younger one (not quite a year old) a 30 min epsom salt bath, separated her, she’s been on electrolytes and medicated feed for 24 hours. I’ve put corid in her water as well. She still won’t walk. She immediately poops water like substance right after she drinks. Her vent isn’t red, it’s still squishy. I’ve checked for egg bound, but don’t think I️ felt anything. Now one of my older birds is showing the same signs. What do I️ do now?

 

[ChattyChickens4Life]

What is squishy? Her vent or her crop? I'm thinking possibly Mareks or a leg injury.