Ruqyah (Exorcism) is the Islamically lawful means of treating sicknesses and other problems.
This science is described in the sayings of Messenger of Allah with evidences . You may find many soothsayers and magicians doing evil stuff using satanic techniques which they wont disclose,These disbelieving/evil jinns/magicians have aggravated the problem and caused more chaos and shirk which also leads to kufr in many cases .This Ruqyah Shariah gig aims to come to the assistance of people who want to get cured by authentic Islamic prophetic means which involve no evil, or harm to others and self.
There are many different symptoms of being afflicted with sihr or jinn possesion or both. Common problems that have been dealt with are people who suffer from anxiety, depression, mental problems etc, marital problems, constant fights within families, excessive violent thoughts, nightmares. It is also common for people afflicted with jinn possesion to have physical problems such as back pain, siatica, etc etc.
What you must bare in mind is that not every health condition or family problem is jinn/sihr related but in order to rule it out ruqyah can be performed on the person or family.