There is no rhyme nor reason to illness, most of the time.  Do not try to analyze where these things come from.  Certainly, lifestyles and life habits contribute to illness, but often I've found NO correlation.  Trying to analyze is not only agonizing, but a waste of very valuable mental energy.  The horse is out of the barn, so to speak, and it is time to rope it back in; pardon the analogy.   Devote all of your energies to comfort and treatment.  Stay the course and never give up.  Kick adversity squarely and resoundly in the ass, and don't look back. 

For at least the past 6 years (don't know why), I have had a close friend or family member affected by a crisis or serious illness...one after the other.   This year, I've had a few of my own.   The episodes have varied in outcome.  All of them make sense, all of them don't make sense.  All have strengthened and either enlightened or baffled me.  I have found the most benefit from strict adherence to accepted treatment regimens, and working closely with a health care provider I like and trust.

I am not a particularly religious person, but I have found in all of these situations that prayer worked 100% of the time, very quickly, and in ways that at first although not evident, later became abundantly clear and manifest. 

So... I will send my little prayer to you and your loved one, all gift- wrapped, and special delivery.