That looks like badly swollen sinuses, which has a number of causes (basically almost anything). If you can get the bird seen by a vet, that would be ideal so you actually know what to treat for. But sometimes that's not really possible (I'm still on the lookout for a vet that will see poultry). If it were MY bird, I'd just do what I generally do with serious-looking illness without a known cause/treatment: isolate the bird and treat with a broad-spectrum antibiotic and vitamin supplements. That may or may not actually cure the problem (always complete the full course of antibiotics, even if they don't seem to be helping!), but even if not, that will generally help the bird's immune system fight off any secondary infection.