Prednisone Questions We Need Help ASAP!

My brother (38) has had neurosarcoidosis for four years now. He has been on high dosages of prednisone and his doctor has tried to get him to 5mg a day, but everytime he does this my brother goes crazy and starts hallucinating, blurred vision, hot flashes, no sleep, depression, and this time he started cutting his knuckles taking off his clothes, and throwing things all on his job. Our family is very worried becasue he's been taking his meds, but he cant seem to stop these side effects. Is there anything he can do to stop these side effects? I also researched taking a psychiatric drug to counteract these side effects. This is very stressful for our family and for him and we need help.