I have a three year old hen who is very sick. For the last few weeks I have noticed she was lethargic, and not eating as well. There hasn't been any changes in housing or flock,.. and everyone else in the flock seems to be doing very well. Since yesterday she has been humped up, tail down, and hesitant to move much. Not eating much to anything and haven't seen her in the waterer. I looked her over and only thing I noticed is that she seems swelled a little in her abdomen and she has a pasty vent area. I did see her poo and it was watery. Her head (comb) is very red, almost purple. I believe she might be egg bound,...she never has laid very well. Any other ideas?? I haven't had much experience with sick chickens so all help is greatly appreciated,...