Among other symptoms, Vitamin D deficiency causes weak and painful bones, swollen joints and lesions of the skin.Honestly, I wonder if all of this is because his feet hurt? Like, he didn’t feel like eating because he was in pain, etc. I’ve never dealt with it myself, but I wonder if it’s bumblefoot? He doesn’t want to climb to the top level of the cage and doesn’t want to perch. I assume because his feet hurt!
He should spend several hours in natural sunlight in addition to a daily supplementation of vitamin D3 + calcium.
Read up the severe effects of natural sunlight deprivation/vitamin D deficiency which cause a plethora of health symptoms.
I hope he gets better soon.