“”It is an obligation to listen to the doctors (Maharik Shoresh 159, Shevut Yaakov 1:65, Yalkut Yosef Kitzor Shulchan Aruch Laws of the Doctor and the Obligation to be Cured 2).”
This is a misquote from those seforim. I checked the Maharik (http://www.hebrewbooks.org/pdfpager.aspx?req=1142&st=&pgnum=178&hilite=) and the Shvus Yaakov (http://www.hebrewbooks.org/pdfpager.aspx?req=1519&st=&pgnum=31&hilite=), they do not say that a person is OBLIGED to listen to every health pointer a doctor might give you. They say that we can RELY on a doctor. They’re discussing Niddoh and Tvilo shalos. For example, if the doctor says that wine on the hair doesn’t tangle the hair, you can RELY on him that this won’t cause a chatzizo.
So, for things which halacha dictates, you accept the doctors point of view. Something the doctor says is dangerous to the point of being life threatening, you can rely on him to be right, and therefore this would be included in the issur of sakonas nefoshos (see Rambam Rotzeiach perek 12). However if it may just cause non-fatal illness, I am unaware of any halocho reason that you can’t do it. Furthermore, someone who is already ill even with a fatal illness, I am unaware of any halachic chiyuv to heal himself. Inasmuch as there is no chiyuv, there is no reason for him to accept the doctors opinion if he thinks he knows better, as even if he did accept the doctors opinion he doesn’t have to do it.
DISCLAIMER: I’m not sure what I’ve written is true. Just varfing a svoro. If anyone knows better please lmk.