Prolapsed vent !!!

[Karen12]

I have a polish hen who I have been trying to get rid of the mites/lice on for MONTHS! With no avail, today I went out to find she has prolapsed her vent. I have brought her home, but she is not able to stay since her infestation is so bad. I have pushed her vent back in about 6 times so far, but every time she poops it comes right back out. I have put in preparation H as well. Advice needed! I can keep her in a carrier back out at the farm, but I guess I'm wondering what else to do help!!!