My DH is schizophrenic. Many issues can be managed with medicine as well as other management like therapy and lifestyle management (such as ensuring enough sleep/stress management to prevent breakdowns). From a carer point of view, these things are often the worst when they first come to the forefront and become milder through conscious effort and understanding what's going on -- but the first while can be very rough for everyone. Obviously not every person with schizophrenia goes through the whole remit of issues, it varies a lot, but I can give you the common stuff.
The main issue of schizophrenia is seeing and/or hearing things that are not actually there. The hallucinations can be as 'mild' as seeing a flashing light that isn't there to very frustrating/draining as hearing the phone ringing when it isn't to extremely disturbing as seeing a person die in a graphic manner in front of you in a public place (and having to restrain yourself from reacting/trying to save the person for a moment to see if anyone else is reacting as that is the only way many people with schizophrenia can tell if what they are seeing is real or not they can even feel things in response to what they are seeing so if they see someone step in front of a bus they often feel the 'bump' of going over the person even if no one else feels it). There is the common portrayal of hearing voices that aren't there telling the person what to do, but clear ordering voices are quite rare, it's far more common to hear like a whispering that you can't quite make out. My DH describes his like a group talking about his life in Olde Nordic in his head he gets a feeling of what's being talked about (negative or positive), but the words don't make sense. The more in control/healthier the individual, usually the milder these things tend to be.
Another major part of it is emotional bluntness. It can take an effort for the person to care, to understand why doing X is important, or why doing X is more important right now than doing the Y they want to do. This can also lead to mood swings (the ups and downs), catatonic episodes as a response to stress, anxiety, paranoia particularly if the hallucinations aren't controlled/understood. There also has been some connection with schizophrenia and memory issues, but it's debateable about whether it's part of it or a condition that commonly runs alongside schizophrenia like paranoia.
The misunderstanding of it is a huge problem. My DH even had a close relative he respected tell him he needs to give up all his fantasy related hobbies and movies to 'cure' it (Lord of the Rings & Warhammer are not contributing factors to mental illness, even when enjoyed by grown men...). Though the first couple of years after it began were quite rough, it does get better & manageable for most people.
I hope your DSS gets the care he needs.