My son was taking Kratom along with other recreational drugs for a few years (he is now 28). When he tried to stop taking it he went into a state of psychosis and had to be intubated until the withdrawal symptoms passed (5 days). The doctor said he had seen the same thing happen before with Kratom withdrawal. There is very little information about how people respond to it and it can be very dangerous. Each person is different of course.
I have fibromyalgia and have suffered from chronic pain for years. I am certainly not opposed to alternative treatments but in my experience, Kratom may not be worth the risk.