Capillary worms can cause swelling in the crop and esophagus, and they're way too small to see, so you could try worming her and see if that helps. Capillary worms can be had to treat... If she were mine I would give her Safeguard liquid for goats or Safeguard paste for horses at 0.5ml per kg (0.23ml per pound) orally for five days.
-Kathy
-Kathy