Help!!!! Mandarin drake will not walk or stand up

[Mandarinducks]

Hi my female mandarin has been sitting on eggs in her nesting box for a few weeks, but it was peculiar because my drake gets in the nesting box with her as if he is lonely. He has not ate very much in the last few days. Today I came to check on him and he couldn't get out of the nesting box, so
I helped him out. once I had got him out he would not walk, but he still seems alert and he is still drinking. I did ad electrolytes to his water though. Please Help!!

 

[Mandarinducks]

I think it may be worms, but he may just be weak because he is not made to fast in a nesting box like the female does.