2yr old hen with white gritty stuff stuck inside vent

[doubleband]

I have a hen I noticed was bleeding and loosing feathers on her rearend. then noticed it was from the others pecking. she has poop just running down her so I have tried a warm bath and inspecting the inside of her vent. I found her vent has white gritty ( looks just like crushed calcium I feed them) stuck to the lining of the vent. it just seems she cant push the fecies out because of the blockage. the soak in water would not dissolve them and I could not pull them out without making her bleed. any help would be great. thanks