Hen in severe respiratory distress. What can I do right now?

My hen suddenly started having trouble breathing today. She is taking deep labored breaths every time, wheezing, and stretching her neck to breathe. She is not constantly open mouth gasping, but it’s every breath.

I also noticed her crop is very full and doughy, and she passed some yellowish discharge from her butt.

So far I have:

• Isolated her • Tried steam therapy • Offered water (not forcing now) • Keeping her upright and calm 

I tried to tilt her slightly to empty the crop but stopped because she was struggling to breathe.

No eye swelling or discharge.