My nephew has schizophrenia and when he is psychotic he refuses to clean. He also has some delusions about using utensils and will only eat with his hands. He also believes that he doesn't need to wash. Perhaps your son is psychotic and has these type of delusions. You said he was diagnosed with depression and anxiety so it may be related to his depression. When people with bipolar has problems with hygiene, it is usually because they are depressed.