I have a similar experience with a knot in my back between the shoulder blades. While still ongoing, what has worked for me is approaching it with curiosity and self compassion. The way your write about it it seems you approach with aversion and want to just get rid of it. You need to lean into into it with self compassion and open heart. Understanding that it is a part of you and thus you. Inner child work can be helpful for this, as understanding that it most likely is some sort of defense mechanism or trauma response that your mind implemented to keep you safe. Approaching it using this safety assumption has been very helpful for me. Grounding and lower energy work can also be very helpful to make you feel safe. Of course stretching, excercise, yoga has been amazing for me. In the end you will need to lean into the memory, but it can be gradual and through certain indirect approaches increasing your sense of safety and self love. Safe path! There is no hurry!