Ok...Sorry you're going through this. Hopefully lemondrop will be all better soon

It's so confusing.... of the above symptoms, the only ones he has are sleeping during the day, head tucked over wing feather, and he did have weight loss though I'm happy to report he seems to have put some weight back on.Signs of Canker/Cochlosoma include: diarrhea, yellowish or bright green droppings, undigested seed in droppings, butt pumping, wet vent feathers, sleeping during the day, head tucked over their wing feather, weight or feather loss.
Maybe the gulping was vomiting? Though he never actually expelled anything he could have been vomiting just in his throat. The froth at the beak part is confusing - just this past week, he is developing a brownish substance on the upper corners of his mouth but it looks hardened like you could scratch it off with your nail. I don't know if this is what is meant by frothing (that almost suggests something wet) but then sometimes I think this is the beginning of scaly face mites though it's really not on his face, only his beak. I have the Ronex on order - I think I will do as suggested and use it at 4x strength for the first few days (says is safe and can be used in difficult situations).The common crop form of canker is the one most breeders are familiar with, the vomiting bird, the bird with froth at the beak,