Does your body talk to you? Does it say things like, "Feed me! Pamper me! Let me sleep!"? Do pain signals on the inside ever sound the alarm just went you're about to go out the door to church?
Do you pray for ears that are ringing but find that they're still singing, "this problem simply will not go away"? What is your body telling you?
Is God warning you to take better care of yourself?
Or could it be a fiendish spirit of infirmity, an uncalled for squatter taking up residence where it has no right?
I John 4:1 tells us to "believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world."
Well, what if the word "symptom" is substituted for the word "spirit"? The passage might then read, "Believe not every symptom, but test the symptoms, whether or not they are from God. For many false feelings have gone out into the world."
If the symptom is a lie, then you need to resist it with scriptures such as "By His stripes we are healed" (Isaiah 53:5,KJV) and "Bless the Lord... who forgives all my sins and heals all my diseases (Psalm 103:1-3, KJV)."
Don't assume every sickness is a flesh thorn. But if it is, what is God trying to teach you through it? Is He teaching you to run to the doctor for medicine? Is He teaching you to endure thorns patiently? Or is He teaching you to fight the fight of faith and believe Him for healing?
Remember that Satan is the accuser of the brethren (Revelation 12:10). But God is merciful and forgiving. He delights to heal! He created you to serve Him, not lie in bed with pneumonia. If you are a new creature in Christ, then all things are made new. Old things (like sickness) are a thing of the past. Why not treat them that way?
Believe not every symptom, but test the symptoms, whether or not they are from God...