First, she is absolutely beautiful! Second. I just went through this. My hen had the exact same symptoms. No other symptoms of respiratory distress other than the gaping and gasping for air. No mucus, no runny nose, no nothing. The screaming is most likely an expellitory response (an aggressive cough to clear airways or blockages.) Which my hen would do too. Especially while eating or drinking. My hen wouldn't do so either. I had to force her to eat and drink. Shes completely back to normal aside from a random cough here and there. You can check out my post and see if you think its the same and see how i treated it.