Seeking advice

Personally I wouldn't go down the prednisone path because there is no future there.  Everything should ideally be geared to long term maintenance because you are in this for the long haul.  Not much point to taking something that you will simply need to give up. Long term higher dose prednisone use causes structural damage of it's own and as I said, I don't think a reputable doctor would go there.  It is common to be given dose packs of prednisone to essentially snuff out a flare.  One thing you will find is that autoimmune diseases come at you in waves.  You can be feeling relatively alright for awhile and then you get hit with a wave that is referred to as a flare.  I have been given dose packs which can be effective in bringing you back to somewhat of a baseline.  But it's use is finite.  You take it for the length of the dose pack which is around six days of so.  For me I often get my best relief after surgeries.  I have had four spinal surgeries and now have six of the cervical vertebrae fused together (technically it is four cervical and two thoracic vertebrae).  But it is common practice to be given heavier doses of a prednisone derivative after spinal surgery to prevent inflammation from the carpentry that they do on the spine.  I often feel wonderful for some period after surgery beyond just what the surgeon has fixed.  I once told the surgeon he was a magician fixing my lumbar and cervical problems in one surgery.  Unfortunately it does not last.

?You made a point earlier about the biologics being hit and miss as well as many of the other treatments.  Good for one person and not as good for someone else.  I believe that is because we are still treating the symptoms and not addressing the underlying causes.  Even the biologics are not all the same.  Some of the newer ones like Cosentyx have a different mode of action than the older ones like Remicade.  One biologic may help you while another won't. I am even trying a diferent variation of a biologic that I rried before.  I took Simponi in a self injectable form with little effect before and now my rheumatologist is trying Simponi Aria which is an infusion form of the same medicine which she has higher hopes for.   It is a trial and error process but unfortunately that is true of many of the autoimmune diseases, not just AS.  It can be as much of an art form as it is science.  You have to find what works for you which includes drugs and diet.  Here's hoping your boyfriend can find that best combination for him.  Doing the research that you are helping him with is the key to a good start.  Best wishes.