I think the brand is Zupreem, they make extruded pellets that can serve in place as a substitute for veggies. Maybe she could try those with him? I know some doves can/will eat them. If not I wouldn’t worry too much. Do you have any idea on the make up of the seed diet he’s currently on?
I know...
It doesn’t look so bad in the picture of him dry. Long life and normal behavior are a good sign that it’s not too serious.
Maybe it could be a diet related issue, what’s he eating?