Chickens bum bleeding. (How to stop the bleeding?)

[Soy sauce the chicken 1]

I'm a clueless teen and my hens bum was bleeding this morning, she was fine yesterday but when I went to go feed them today her bum was bleeding. I only noticed when one of my other hens pecked at her bum. She's been having some liquidy-poop lately,I can't find anything anywhere on how to stop the bleeding and to help her. Please send any possible solutions.

 

[DobieLover]

Please post pictures of the area.
If it's warm where you are and she's been having problems with diarrhea, she may have flystrike.
She may also be getting vent pecked. Either way she needs to be removed from outdoors, placed inside, soaked and cleaned up. If you see maggots floating in the water she's in trouble and you need to get rid of all of the maggots as they continue to hatch by doing multiple soaks a day.