Full-blown schizophrenia affects about 0.32% of the population (around 24 million people) as a conservative estimate. There are other schizophrenia-spectrum disorders (schizoid, schizotypal, schizophreniform) that account for another ~1.9%.
It's on the uncommon side of incidence (significantly less common than depression or anxiety, for example), but your likelihood of having these issues increases proportionally with how prevalent it is in your genetic history. Having more than one relative increases your risk of developing all schizophrenia-spectrum disorders (and also, autism - they are related), and this risk increases with other conditions of environment such as trauma and drug use.
However, psychosis is only one symptom of schizophrenia. And hallucinations are only one symptom of psychosis. So if you're seeing/hearing things that aren't there? You need to get evaluated, because it could be literally anything, including secondary psychotic symptoms with PTSD. You could have a tumor, cancer, depression, epilepsy, bipolar, DID, pharmacological side effects, etc etc etc.
Really get yourself to a doctor, if it's possible. And if it does turn out that you may be dealing with an issue like this, it isn't the end of the world. There are treatments for all schizophrenia-spectrum disorders, and even if the treatments aren't effective, you can still build resilience in your life that will help absorb/mitigate the worst of the disease.