I have a duckling that is quite distressed and lethargic. It is peeping almost constantly and wont settle. It has been vomiting up a fair bit of food and it seems to be having problems doing a poo. It did a large poo a little while ago, but now it is just doing small white runny poos with great difficulty. I have tried to clean the vent area (by soaking in warm water) which is a bit dirty and smelly but it hasnt seemed to help. As far as I am aware it hasn't ingested any food like lettuce, just duckling starter crumble. Any advice as to what may be wrong and how I can help?