Isn't illegal for doctor I see kept ask me why I have a humana-medicare card. Then forcing me to go see psychologist, l refused then he stopped see me?

Not illegal. Your doctor may be concerned about the "complex back pain" you have listed as a clinical finding, and is trying to understand all possible information about this. S/he may wonder about you being on medicare at a young age (if you are). S/he may refer to to a psychologist to help any stress/emotional issues which can contribute to pain, and may decide not to see you if you won't work on this.