From the Catechism:
2278 “Discontinuing medical procedures that are burdensome, dangerous, extraordinary, or disproportionate to the expected outcome can be legitimate; it is the refusal of ‘over-zealous’ treatment. Here one does not will to cause death; one’s inability to impede it is merely accepted.” [More not written here]
2279 “Even if death is thought imminent, the ordinary care owed to the sick person cannot be legitimately interrupted.” [More not written here]
With that in mind, we have a responsibility to care for our bodies as they are temples of the Holy Spirit. Without a diagnosis, no reasonable decisions can be made. You have to first know what you are dealing with, receive the options, then prayerfully make a decision.