It's all psychosomatic. The trouble is in your unconscious mind and/or your conscious mind and it relates to feelings you do not want to face.
If you get into psychoanalytic or psychodynamic therapy and express the poison in you (we all have it, so I mean the generic "you"), you remove it from your body and your symptoms will disappear.
Remember: this illness is caused by your MIND, not your body.
The cure lies in your MIND, but not your conscious mind. It lies in getting rid of the anger, pain, hate, and other feelings that you are afraid to experience.
You either decide you are brave and believe people like me who say relief can be immediate in this kind of therapy, or you decide you want to "conquer" DP/DR.
You cannot conquer it; don't kid yourself. Eventually it will cause a worse psychosomatic disease in your body, and may even cause a somatic illness.
Your feelings must be felt or they will make you sick.
It does take bravery to face what we are afraid of, but that's what has to be done if you want to recover.
Getting the upper hand on DP/DR by ignoring it, being busy, and so forth, or drinking alcohol, just postpones the final denouement, which you may not even survive at all.
You have a psychosomatic illness. That means it is CAUSED by your mind and your emotions. Only healing those will save you.
Get therapy now if you want to live the rest of your life normally.
Everybody resists experiencing old, excruciatingly painful feelings that they have buried inside and tried to completely forget about. But our bodies are wise. They know. Your psychosomatic illness is crying out to you, "Save yourself now!" It won't stop crying out, but the longer you ignore its message, the more severely it shouts. The next time, you may have paralysis in a limb, lose your immune system, have a heart attack, or go totally mad.
Face your feelings, face your fears, face the source of your symptoms with a trained professional and you will be relieved of all this.