Seems abit weird that the dr can not rteat both especially as both are serious!!
Have you looked into natural or alternate therapies, including meds that are not so often prescibed??
Try going to a search engine (google or yahoo etc) & querying alternative treatments for ms, same re bp, also look in phone book for naturoopaths, homeopaths etc they might be of use.
Many natural meds can be taken with pharmaceutical meds so this could be a matter of prescription meds for one natural for the other.