Poor girl 
My first thought of looking at the swelling is Ascites (fluid) which is usually a symptom of an underlying condition.  Sadly, a lot of times the cause (or name) of a particular reproductive disorder is not known until then hen has passed and a necropsy is performed, then you may be able to tell whether it is Internal Laying, Salpingitis, Egg Yolk Peritonitis, cancer, etc. 
You got no fluid when you tried to drain?  So it's probably more solid, like egg matter in there, but that's just a guess on my part.
A hen's body temperature is normally 105-107F but you mention it was like a camp fire, I would again hazard a guess that she has infection.   Sometimes an antibiotic may help extend life and give them some relief, it really depends on the cause.  My first choice would be to give Baytril (she's not laying eggs, but if she does, throw those away for a few weeks), second choice would be Amoxicillin.  Both can be ordered online.
I would watch that the others are not picking at her bottom.  Treat the lice (what are you using?) and see that she's drinking well and eating.  
Thank you so much for answering! I have an animal thermometer , I'll take her temp here shortly after this monsoon we're having quits. I just watched that video, I'll try the draining again, maybe I went too deep. I'll def get some baytril so thank you for that link. I put her in a little extra coop I have ''chicken hospital'' and when I let her out this morning it wasn't as red. How would you know other wise if it's an egg laying problem? Would u just know if she passed and I opened her up to tell? She's not doing that ''penguin'' walk like she's egg bound. 
For the lice, I soaked her butt down with cowboy magic I have for the horses and picked the egg clusters off, then I dusted her real good with some poultry dust that pertains permethrin.