Sick Hen - Should I Cull?

I have a 2 and 1/2 year old Production Red hen. She was acting lethargic a few days ago, not eating like everyone else. I picked her up, felt her crop (for impaction or sour crop), and she vomited clear liquid (I presumed water - there was no smell). I held her upside down and massaged her crop. She vomited water and some small red grains from the scratch I feed them. Not sure why this was the only food... but it was all I could get out. Her crop wasn't hard, nor was it large and squishy. I quarantined her and she was gaping, but that was from turning her upside down I assumed. Gapeworm is really rare in our climate - I live in the desert. Still, I didn't hear any wheezing, coughing, or sneezing from her.

Later that evening I came out and she was drinking just fine and seemed eager to rejoin the flock, so I let her go. She promptly ate dinner and seemed to be fine. So, I figured she was just having trouble getting the scratch down or something.

Fast forward to yesterday: Same hen seems lethargic again, but is still attempting to eat and drink. Her comb is turning purple, as if she's not getting enough oxygen and she's still gaping from time to time but with no coughing, wheezing, or other sounds. I looked inside her mouth and can't see any blockages. I picked her up and she feels like a skeleton. I can feel every bone. I don't know why I didn't feel that a few days ago, but it's very apparent now. Her crop feels somewhat squishy, but I soak their feed and she was eating some of it. As I massaged her crop she began gaping again. I figure it was a blockage, so I got some water and syringe fed her some water, while massaging her crop. Now a foul smell is coming from her mouth as I massage. I turned her upside down and massaged it, but almost nothing came out.

Here's why I'm confused:

Gapeworm? Seems unlikely because she makes no sound when she opens her mouth, no one else has this, and in our climate it's extremely rare.

Heart Disease? Would explain the purple comb, but not the other symptoms.

Blockage? Would explain the gaping, lack of eating, body condition and eventual sour crop BUT does it explain the purple comb?

I do not have access to a vet, nor would husband pay for one for a chicken. I can worm her and treat sour crop, but it seems like she's starving (body condition). I have no way to do exploratory surgery to find out where the blockage is. Should I cull or treat? I feel like I've caught it so late at this point that she's suffering and slowly starving to death.