Sometimes, a real prophet can prophesy something that you are not comfortable with. God tells us some things sometimes just for our information, or so we can do something about them.
Sometimes, negative prophecies can come to you directly from God, either in a dream, trance, or even in an audible voice.
The first thing you can do is to cry to God to reverse the prophecy (2 Kings 20:1-11) or get prophet with a higher anointing to cancel the negative prophecy.
“Negative prophecies, even when genuine, can be reversed.”
Memorise: Turn again, and tell Hezekiah the captain of my people, Thus saith the Lord, the God of David thy father, I have heard thy prayer, I have seen thy tears: behold, I will heal thee: on the third day thou shalt go up unto the house of the Lord. (2 Kings 20:5)