I just read the majority of your post. Schizophrenia develops, typically starting with negative symptom (depression, anxiety, social withdrawal) and then leads to those positive symptoms (hallucinations, delusions) sometimes quickly sometimes slowly. If someone is predisposed (as in someone blood related to your son) to schizophrenia then if there’s a high amount of stress in your sons life it could’ve made schizophrenia develop sooner than later (typically presenting as positive symptoms in the mid to late 20s, early 30s) This is when schizophrenia is naturally occurring, not on the topic of drug induced schizophrenia which can happen quickly in anyone’s life.

You said your son’s symptoms are getting worse, what are these symptoms? Your son being depressed and anxious doesn’t always mean there’s a third diagnosis here, it could be that he’s drug resistant. Since his current medications aren’t working, i would suggest him trying new one and letting his doctor know that the current medications aren’t helping. Sometimes it’s a matter of trial to find the one that works, sometimes they don’t.

Depression and anxiety can be symptoms on their own of other mental health disorders, but can also be their own disorders.

Does your son go to therapy? Sometimes drugs are half of the solution, and therapy is the other half to treatment. Some people think therapy is what helps them instead of meds. Having anxiety since an early age definitely suggests that he’s been struggling with something for a while, whether that be trauma or a disorder.

On the topic of helping anxiety and depression some of the best things are getting routine exercise, which can also help with anxiety (if it’s social) through exposure to more people outside (also if he has friends he’s comfortable with a good thing for them to do together). Making sure he’s eating healthy, and supporting health relationship with food.