Beware of the Great Deceiver, Satan, as he can also heal, but his healing will not last as he is the shapeshifter.
A healing might happen because you have changed your lifestyle and are getting more sleep, avoiding high sugar processed foods, doing more exercises, and/ or simply walking more, and drinking more water. Sometimes people suffering from cancer go into spontaneous remission simply by going on a vegetable juice diet or by having their root canals removed.
This is why we cannot trust in those miracles used as a proof of sainthood especially those recent miracles of the so-called modern saints who have been recently canonized or who will be canonized in the coming months by the Vatican II church.
Some of these modern saints may have been righteous, but others were not so righteous, instead they were ecuмenists and freemasons. It is through their works and writings that you might be able to discern who is righteous and who is not.
Ultimately, it is best not to venerate the modern saints, but to venerate the true ancient ones, such as the Holy Apostles and Holy Fathers of the Church, especially St. Nicholas of Myra who in his devotion to the True Faith slapped Arias the heretic. It was the Blessed Virgin who came to his defense when the Fathers of the Ecuмenical Council were about to discipline St. Nicholas for slapping Arias as it is sacrilegious to slap a fellow clergyman.
To give a modern example. A true story was told during a retreat. There was a Dominican priest who was well known for his wonderful sermons and retreats. People praised him as a saint during his lifetime. There was also a Dominican priest who was avoided by people because he was drunk most of the time and could not speak coherently. Both of these priests were in the priory infirmary dying from extremely painful pancreatic cancer.
On his deathbed, the "saintly" Dominican Priest cursed God for causing this painful cancer. Where was his reward for rising early, being punctual, fasting, avoiding alcohol, spending all his days and many nights in silent prayer and contemplation, and writing all those wonderfully well written sermons and books. Was this the way God was rewarding him? He died totally shocking all those around him by his blasphemy.
The alcoholic priest was greatly grieved to hear how the other priest had died. He asked all to come to his bedside, where with tears in his eyes, he profusely apologized for his numerous sins, for his alcoholism, his bad habit of smoking, his lack of punctuality, his lust, his laziness, his lack of silence, his scandalizing others, and his gluttony. He pleaded for all the friars to stay and to pray the prayers for the dying that he may persevere in the Faith and not lose hope in his final moments. He stated that he deserved Hell, but that this painful cancer had brought him to his senses through God's grace.
May we, like the prodigal son, be saved through repentance.