Energetic hen won't walk, husband wants to put her down tomorrow

I have a regular brown egg laying hen (Hennie)  that just suddenly took ill yesterday morning.

Here is some info....

Housing... insulated coop with access to outdoors on decent days, which is about 5 or 6 days per week.

bedding... shavings and straw, straw mostly for nesting boxes.  cleaned frequently, husband never allows it to be wet.

co-habitants... 1 rooster and 22 other healthy seeming hens, various age and breed  (1 exception, more blood spots in eggs)

Food... layer mash with treats daily.  treats recently have been cracked corn, small amounts of bread and lettuce, tomatoes, etc

   the only unusual thing fed was leftover cantelope. 

Water... always cleaned and replaced twice a day.

symptoms.... she seems lighter.  she just sits there, on her feet.  feet and muscles seem fine and she can stand, she just seems weak or lacking desire...

   she makes lots of cute arrr arrr sounds.  doesnt sound distressed, just like she wants me to know something.  she is isolated, she likely is lonely.

really stinky blobs of green runny poo.

crop seems kind of full constantly... husband has been feeding her cooked eggs, olive oil, yogurt.  he has been massaging her crop.  it seems smaller in the am though, but not normal size.  tonight it is big but kind of soft.

her abdomen feels normal.  her comb color is good, her eyes are bright.  we think she is less than 2 yrs old.

she eats really well and seems really thirsty.

she is not broody.  I dont think she has laid an egg during these 2 days.  also i dont think this co-op breed hen would go broody would she?  also she is not nesting or anything.  husband found her just roosting at 10am while everyone was outside so he had a closer look. 

Any help would be appreciated!

I gotta tell you..... in our colder climate, I don't think worms are a problem here. 

I have gone to the feed stores and the vets around here and when I ask for dewormer, people look like I have 3 heads.  I am not neive, I bet we do have worms but likely to less of an extend to you guys in the south.  if i could get a dewormer in canada online, i would order it to have on hand.  suggestions are appreciated!

Hennie is doing better tonight.  we took away her food besides 1.5 hardboiled eggs with about 4 tbsp full fat greek yogurt and 2 tbsp olive oil.  Her crop is now half the size.  Her crop feels squishy.  You know those stress balls that you squeeze and it holds its shape for a moment.... like that but not so hard. 

Is that impacted crop or sour crop?  how do you tell the difference?

She was much more lively tonight, up walking around.  drinking lots. 

Her poop is clear liquid with the odd solid piece. 

Not sure if she is on the mend or not, fingers crossed.