I'm in the "check the crop" camp. When in doubt always check the crop in the evening when they roost up, It ought to be golf ball sized. NEVER let a chicken go to be empty, it affects their health really badly! Also pay attention to
what she is eating, sometimes they fill up on the dangdest things! I had a new hen fill up on grit instead of food, that was a scary touch-and-go to get her fixed and keep her alive! So any thing is possible with a chicken. "sour crop, impacted crop"
check for parisites, on the skin, feather shaft; sometimes you will look and look at your whole flock and you may finally one day see a louse running; by the time you catch the one there is a whole ton playing hide and seek in there! If you actually see an actual
infestation it is dire. "lice, mites"
check their poop. Gross, but that's how you know. Watery can mean not enough food, constipated, sick drank too much water; bright green (not the usual green) can indicate liver failure...... I have the poop chart if you see something you don't know how to i.d. "poop chart"
Check the comb for paleness, that can indicate worms or mites. Some mites are nocturnal,so you won't know by looking. "worms, northern fowl mites"
Look at and feel the ankle and knee joints for swelling, look for swelling on the footpad. Or a dark scab without swelling. "M.S, gout, bumblefoot"
At the bottom of this post in my siggy are links to medicine charts, diagnostic charts, whatever i have found to be helpful in my searches. If you go to one of the diagnosing links and search the "_______" you will get an explanation of the symptoms and how to treat that illness.
Feel along her breast bone to the bottom, feel along her bottom of her starting from the bottom of the breast bone to her nethers, you are feeling for a large lump on each side of the ridge which could be a "stuck egg or constipation." If there is a stuck egg or constipation and it is bad the poop will be very watery, sometimes lacking the "whites". It it turns really yellow she's not long in this world, that means her system has shut down. In the case of these the hen will not be wanting to eat, since she can't poop.
Also do a search on "internal laying", i have seen many stories this year with the wyendotte's having reproductive issues, and that also produces those symptoms. If this is so, there's not much you can do. You can prolong her life by antibiotics to keep the egg from rotting inside her, and stick a needle in to drain out the yuck, but in the end it all ends the same
