It sounds to me like he has a mental condition, possibly schizophrenia, which is being exacerbated by alcoholism and/or drug abuse (and/or, he's not taking an Rx).
No, it's probably cirrhosis of the liver, end stage, due chronic alcoholism. The cycles of abnormal mental behavior are due to ammonias building in the bloodstream. Get flushed out with diuretics, be okay for awhile, lather, rinse, repeat, until the kidneys are too damaged to continue the burden of what the liver should be doing, then death within 7-10 days of kidney failure.
It's a nasty way to go.